Decoding the Mail: Understanding the Types of IRS Letters

Receiving a letter from the IRS is rarely a cause for celebration.

That official-looking envelope in your mailbox can trigger a wave of anxiety, leaving you wondering, “What do I owe now?” or, “Did I do something wrong?” It’s no wonder that dealing with the IRS is a common source of stress for taxpayers, especially those facing a complicated tax situation or potential audit.

Before you let those worries take over, however, take a breath. Understanding the types of IRS letters and notices — and knowing what actions to take to follow up on them — can help you respond to these communications with more confidence.

Why Does the IRS Send Letters?

The Internal Revenue Service (IRS) sends out an enormous volume of letters and notices to taxpayers each year. These communications serve various purposes, all aimed at ensuring compliance with tax laws and proper management of tax accounts.

Here are some of the reasons you might receive a letter from the IRS:

Request for Information

The IRS might request additional information or documents to verify details on your tax return or clarify discrepancies. Sometimes, this might be to verify your eligibility for a tax credit or to confirm income information the agency has received from other sources.

Account Update

Some notices might provide updates on your tax account, such as changes to your balance due, confirmation of payments received, or adjustments to your refund amount. You might also receive a notice if the IRS has applied part or all of your refund to offset other tax debts or outstanding federal debts, such as student loans.

Notification of Balance Due

If you owe taxes, you’ll receive a balance due notice outlining the amount you owe and instructions for making payments.

Notification of Refund

In the best-case scenario, the IRS might send you a letter confirming a refund, explaining the amount you’re due and when to expect it.

Proposed Changes to Your Return

If the IRS proposes adjustments to your tax return that could impact your tax liability, they’ll notify you through specific letters. This might involve a change to your income, filing status, or deductions.

Notification of Intent to Take Action

In more serious situations, the IRS sends letters outlining its intended actions if tax debts remain unpaid. These might include filing a federal tax lien, levying assets (seizing property or wages), or initiating other collection efforts.

Understanding why the IRS is sending you a letter is the first step to taking the appropriate action.

Identifying Your IRS Letter or Notice: What to Look For

It’s important to read the letter or notice you’ve received carefully before you panic. Each communication will include key identifying elements that will help you decode it.

Here’s what to look for:

Notice or Letter Code

In the upper right corner, you’ll find a unique code, often starting with “CP” or “LTR,” followed by a series of numbers. These codes provide a clue as to the letter’s purpose.

Date

Take note of the date the letter was issued. You’ll need to know it in order to meet deadlines for responses or payments.

Tax Year

The letter will specify the tax year it pertains to (e.g., 2023) so you can easily locate the corresponding tax return. This might be for the current tax year or a prior tax year.

Tax Period

For notices related to employment or business taxes (like quarterly payroll tax filings), the tax period in question will be identified.

Tax Period Shown

Some notices might reference a specific date range or period within the tax year.

Outstanding Balance

If you owe money to the IRS, the notice will state the amount due.

Requested Information

If the IRS is seeking specific documents, tax records, tax information, or additional information, the body of the letter will outline those requests.

Due Date

Pay close attention to any deadlines mentioned in the letter for responding, making payments, or taking other actions. There could be consequences if you fail to take appropriate action by these deadlines.

Once you understand these key elements, you’ll be better equipped to interpret the letter’s content and respond accordingly.

Common IRS Notices

The IRS uses a vast array of notice and letter codes to communicate with taxpayers, each of which has a specific purpose. Here’s an overview of the most common types of IRS letters:

CP Notices

CP notices often relate to individual income tax returns or taxpayer accounts. They can range from simple balance-due reminders to more complex notices about proposed tax changes. Some of the most frequently sent CP notices include:

CP14: Notice of Balance Due

This is one of the most common notices. If you owe taxes and haven’t paid the amount by the due date, you’ll receive a CP14 notice outlining your balance and payment options, as well as the potential consequences of non-payment.

If you’re unable to pay the full balance, the IRS might allow you to set up a payment plan, also known as an installment agreement, to pay off your debt over time.

CP2000: Underreporter Inquiry

If the IRS receives income information from your employer, bank, or other sources that doesn’t match what you reported on your return, they’ll send you a CP2000. This notice will outline the discrepancies, propose adjustments to your original return, and calculate the potential additional tax or refund owed.

CP21B: Notice of Requested Changes

This notice serves as confirmation that the IRS has made the changes to your tax return you requested for a specific tax year. If you get a CP21B in the mail, you can expect to receive a refund check within two to three weeks.

Math Error Notices

While not technically a distinct category, these notices are often included with CP letters. The IRS might send a notice (for example, a CP2000) that identifies a simple mathematical error on your original return. The notice will explain the error and how it affects your refund or balance due.

Notice of Federal Tax Lien Filing (LT11)

An LT11 notice is serious business. It means the IRS is taking steps to secure their claim to your property (real estate, vehicles, etc.) due to a significant unpaid tax debt. This notice typically follows multiple ignored balance-due notices and is a strong indicator that the agency intends to escalate its collection actions.

Notices Regarding Tax Credits

The IRS might use different notices to address credits claimed on your tax return.

For example, the agency might send a CP75 or CP75A notice if there are questions or adjustments related to the Earned Income Tax Credit (EITC) claimed on your return. They could be requesting additional information to verify your eligibility or explaining a reduction in the credit amount.

If the IRS determines that you’re ineligible for a tax credit you claimed, they’ll adjust your return accordingly.

Other Important IRS Notices

Beyond CP notices, the IRS may send a wide range of other notices to address specific tax matters. Here are just a few:

Audit Notices

While any IRS letter can be nerve-racking, an audit notice often triggers high levels of stress for taxpayers. If your tax return has been selected for examination, the IRS will send you one of the following types of audit notices with further details:

Letter 566: Examination of Income Tax Return

This letter formally informs you of the audit. It specifies the tax year being looked at, the type of audit (correspondence or field audit), and the information and documentation you’ll need to provide.

CP2000

As mentioned, a CP2000 notice can also be considered an audit notice, as the IRS is proposing changes to your return based on their findings.

Collection Notices

When a tax debt remains unpaid, the IRS ramps up its collection efforts. These letters become increasingly urgent, culminating in potential asset seizures:

• CP501: Reminder notice: A first reminder that you have an unpaid tax balance.
• CP503: Second notice: A follow-up reminding you of the outstanding amount, indicating that the IRS hasn’t received payment.
• CP504: Final notice before levy: A final warning that the IRS will begin levying your assets if you don’t pay or make other arrangements.
• LT11: Final notice of intent to levy: Confirmation of the IRS’s plans to initiate a levy, which might involve seizing funds from your bank account or garnishing your wages.

The LT11 notice also explains your right to request a collection due process (CDP) hearing to appeal the levy.

Statutory Notice of Deficiency (90-Day Letter)

Also known as a CP3219N, a Notice of Deficiency is sent when the IRS has completed an audit and proposes significant changes to your tax return. These changes often result in an increase in your tax liability (a larger balance due) or a reduction in your expected refund.

The 90-day letter is a critical notice, as it gives you 90 days from the date indicated on the letter to either pay the proposed deficiency or file a petition with the Tax Court.

If you disagree with the proposed changes, you can ask the Tax Court to review your case. You should consider taking this path if you believe you have grounds for an appeal.

Notices Related to Federal Employment Tax or Excise Taxes

Businesses often receive various notices from the IRS related to federal employment taxes (payroll taxes) or, less commonly, excise taxes. They may include:

Notice 941: Employer’s Quarterly Federal Tax Return

This form (and associated notices) covers taxes withheld from employee wages, Social Security taxes, and Medicare taxes. The IRS might send balance-due notices, penalty notices for late filing or late payments, or requests for additional information regarding your 941 filings.

Notice CP250A: Change of Tax Filing Requirement

This notice is meant to inform business owners of changes to their federal employment tax filing requirement, which happens when their annual employment tax liability exceeds $1,000.

What to Do When You Receive an IRS Letter

No matter what type of letter or notice arrives in your mailbox, it’s critical not to ignore it. The IRS has significant power to collect unpaid taxes. While some letters might be simple reminders or requests for information, others could be warnings of impending collection actions.

Here’s a breakdown of the steps you should take to address your recent IRS notice:

Don’t Ignore It

The IRS won’t leave you alone just because you ignore its letters. In fact, doing so will only make things worse. Your best bet is to face the issue head-on.

Read the Notice Carefully

Take the time to review the notice in its entirety. Pay close attention to the following:

• Notice or letter code: Indicates the nature of the tax issue.
• Date: The date the notice was sent.
• Tax year: The year the notice pertains to.
• Tax period: May be applicable for business taxes.
• Outstanding balance: What you owe the IRS.
• Requested information: The specific documents, tax records, or information you need to provide.
• Due date: The deadline to respond or make a payment.

These elements will tell you what the notice is about and what you need to do to resolve the underlying issue.

Gather the Necessary Information or Documents

If the IRS is requesting specific information or forms, locate them promptly and double-check them for accuracy prior to submission.

Respond to the IRS

Whether you’re providing information, paying your balance, or making a request, it’s essential to reply to the IRS by the due date specified in the notice.

Consider Your Options

Depending on the type of notice you receive, you may have the option to:

• Make a payment if you agree with the amount due.
• Request a payment agreement to set up a payment plan.
• Appeal a determination if you believe a tax adjustment is incorrect.
• Request a CDP hearing if the IRS intends to levy your assets.

Make sure to read the included instructions carefully to better understand what steps you’ll need to take.

Spotting IRS Scams

Not all communications that appear to originate from the IRS are legitimate. Here are some red flags that can help you identify potential scams:

Unexpected Contact

The IRS initiates most contact through regular mail. Be wary of unexpected calls, emails, or text messages claiming to be from IRS agents. If you receive an unusual call, don’t give out any personal or financial information.

Threatening Language

The IRS will never threaten you with arrest, legal action, or deportation if you don’t pay immediately. These are tactics scammers use to intimidate their victims into handing over money.

Demands for Specific Payment Methods

Scammers often pressure taxpayers to make payments using gift cards, prepaid debit cards, wire transfers, or cryptocurrencies. The IRS provides a list of legitimate payment options, which you can find on the agency’s website.

Requests for Personal Information via Email or Phone

The IRS generally won’t request sensitive personal information, such as your Social Security number or bank account details, over email or phone. Being asked for this information over these channels should give you pause.

What to Do If You’re Targeted for a Scam

If you suspect you’ve been targeted by an IRS scam or have received a suspicious letter or notice, here’s what you should (and shouldn’t) do:

Don’t Engage with the Scammer

If you’re on the phone, hang up as soon as your suspicions arise. If you’ve received a link via email or text message, refrain from clicking it.

Report the Scam to the IRS

You can report the scam online using the IRS’s “Report Phishing and Online Scams” page. You can also contact the Treasury Inspector General for Tax Administration (TIGTA) at [email protected].

Contact a Tax Professional

If you’re ever unsure about the legitimacy of an IRS communication, it’s a good idea to reach out to a qualified tax professional. They can help you verify the notice, protect your rights, and advise you on the best course of action.

When to Seek Professional Help

While you can handle some IRS notices on your own, seeking guidance from a tax professional is crucial under the following circumstances:

• You’re unsure what the notice means or what actions to take.
• You disagree with the IRS’s assessment, such as proposed tax changes or penalties.
• You’re facing a complex tax issue, such as one that requires you to discuss your tax liability or refund with a former spouse.
• You need help responding to a 90-day letter, understanding your appeal options, or preparing for a CDP hearing.

Issues like these are best tackled under the supervision of a knowledgeable tax professional, who will be familiar with the relevant tax laws and IRS procedures needed to resolve the matter.

How a Tax Lawyer Can Help

When you work with the dependable tax professionals at Tax Relief Counsel, you’ll enjoy the following advantages:

• Knowledgeable interpretation: We’ll break down complex IRS language into clear, easily understandable terms, explaining the nuances of your notice.
• Strategic guidance: Our team will help you develop the most effective response strategy based on your individual tax situation.
• Effective communication: We’ll handle all communication with the IRS on your behalf, meeting key deadlines, submitting accurate responses, and protecting your rights.
• Peace of mind: Dealing with the IRS can be stressful. We’ll take the burden off your shoulders, allowing you to focus on other important aspects of your life.

Contact us for a free, private consultation today, and let us put our experience to work for you.

IRS Notice Codes: A Quick Reference Guide

To help you identify and address your specific notice, we’ve provided a comprehensive table detailing the many types of IRS notices and what they mean:

Notice Code	Description	Topic Category
CP01	Identity theft indicator placed on your account	Identity Theft
CP01A	Provides an Identity Protection Personal Identification Number (IP PIN)	Identity Theft
CP01C	Acknowledgment of identity theft documentation; account marked with indicator	Identity Theft
CP01H	Unable to process return; SSN belongs to deceased person	SSN
CP01S	Identity theft claim received; will contact with refund or request for information	Identity Theft
CP02H	Balance due because of amending return to show Hurricane grant	Balance Due
CP03C	May need to file a form to report ownership change for first-time homebuyer credit	Credit
CP04	Deployment to combat zone; need to file return	Filing
CP05	Holding refund for review of treaty benefits and Schedule A deductions	Deductions
CP05A	Examining return; need documentation	Verification
CP05B	Holding refund; need to verify income	Refund
CP06	Audit of return for premium tax credit; holding refund	ACA
CP06A	Audit of return for premium tax credit; need documentation	ACA
CP07	Holding refund; need to review treaty benefits or Schedule A	Deductions
CP08	Possible eligibility for Additional Child Tax Credit (ACTC)	Refund
CP09	Possible eligibility for Earned Income Tax Credit (EITC)	Refund
CP10	Change made to return affects estimated tax payments for next year	Estimated tax credit
CP11	Changes made to return result in balance due	Balance due
CP11A	Changes to return (EITC) result in balance due	Balance due
CP11M	Changes to computation of Making Work Pay Credit	Return error
CP12	Changes made to correct return	Refund
CP12A	Changes to correct EITC on return	EITC
CP12E/12F	Changes to correct miscalculation on return	Return error
CP12M	Changes to computation of Making Work Pay/Government Retiree Credits	Return error
CP12R	Changes to computation of Rebate Recovery Credit	Return error
CP13	Changes to return result in a balance of zero	Zero balance
CP13A	Changes to return due to error with EITC	Zero balance
CP13M	No tax liability or refund after adjustments for Making Work Pay Credit	Zero balance
CP13R	Changes to return involving Recovery Rebate Credit result in zero balance	Zero balance
CP14	Balance due on unpaid taxes	Balance due
CP14A/B/C/D/E	Balance due on unpaid taxes	Balance due
CP14H	Balance due on Shared Responsibility Payment (SRP)	ACA
CP14I	Penalties charged for not taking out IRA minimum	Penalty
CP15B	Penalties charged for unpaid employment or excise taxes	Penalty
CP15H	SRP assessment due to income change	ACA
CP16	Changes made to return affect refund, offset for other tax debts	Refund
CP18	Incorrect claiming of deductions/credits	Balance due
CP19	Amount of tax owed increased due to incorrect deductions/credits	Deductions
CP20	Refund less than expected due to incorrect deductions/credits	Deductions
CP2000	Underreporter inquiry	Underreporter
CP2005	Accepted information provided; case closed	Underreporter
CP2006	Accepted information provided; awaiting determination	Balance due
CP2057	Need to file amended return	Amended return
CP21A	Changes requested to return result in balance due	Balance due
CP21B	Changes requested to return result in a refund	Refund
CP21C	Changes requested to return, resulting in no change to balance	Zero balance
CP21E	Changes made to return after examination	Review
CP21H	Change to SRP	Balance due
CP21I	Changes to IRA taxes resulting in a balance due	Balance due
CP22A	Requested changes to return result in balance due	Balance due
CP22E	Changes due to recent audit result in balance due	Balance due
CP22H	Changes to return also change SRP	Balance due
CP22I	Changes to IRA distributions resulting in balance due	Balance due
CP23	Balance due from difference in estimated tax payments and amount credited	Balance due
CP24	Changes to return due to difference between estimated tax payments and amount posted to account	Refund
CP24E	Overpayment credit due to difference between estimated tax payments and credited amount	Refund
CP25	Zero balance due to changes in estimated tax payments	Zero balance
CP2501	Payment information discrepancy	Underreporter
CP2566	No tax return received; tax calculated based on income info	ASFR
CP2566R	No response to CP63 (holding refund); tax calculated based on income info	ASFR
CP27	Potential eligibility for EITC	Review
CP30	Penalty charged for underpayment of estimated tax	Penalty
CP301	Confirmation of visiting IRS website and registering for service	Identity theft
CP30A	Penalty reduced or removed for underpayment of estimated tax	Penalty
CP32	Replacement refund check sent	Refund
CP3219A	Information differs from return	Deficiency notice
CP3219N	No tax return received; Notice of Deficiency (90-day letter)	Deficiency notice
CP32A	Call to request refund check	Refund
CP39	Refund from you or spouse used to pay past-due tax debt	Balance due
CP42	Refund amount changed due to application to taxes owed	Refund
CP44	Delay in processing refund due to taxes owed	Balance due
CP45	Overpayment could not be applied to estimated tax as requested	Overpayment
CP49	Refund used to pay tax debt	Overpayment
CP501	Balance due on tax account	Balance due
CP501H	Balance due on SRP account	ACA
CP503	Unpaid balance on tax account; no response to previous notice	Balance due
CP503H	Unpaid balance on SRP	ACA
CP504	Unpaid balance on account; final notice	Balance due
CP515I	Balance due; unfiled prior-year tax return	Balance due
CP516	Missing prior tax return(s); reminder	Filing
CP518I	Missing prior tax return(s); final notice	Filing
CP51A	Balance due on Form 1040/1040A/1040EZ	Balance due
CP51B	Refund due on Form 1040/1040A/1040EZ	Refund
CP51C	Zero balance on account after computing Form 1040/1040A/1040EZ	Zero balance
CP52	Correction to claimed self-employment taxes	Self-employment tax
CP521	IRS installment payment due	Installment agreement
CP523	Installment agreement defaulted; intent to terminate and levy assets	Levy
CP523H	Intent to terminate installment agreement	Installment agreement
CP53	Direct deposit of refund unsuccessful; reissue sent by mail	Direct deposit
CP53A	Direct deposit unsuccessful; research in progress; reissue in 8–10 weeks	Direct deposit
CP53B	Direct deposit unsuccessful; research in progress; reissue in 8–10 weeks	Direct deposit
CP53C	Direct deposit unsuccessful; research in progress (questionable payments)	Direct deposit
CP53D	Direct deposit rejected; issuing paper check instead	Direct deposit
CP547	Receipt of Form 2848, Form 706, or Tax Information Authorization; Centralized Authorization File (CAF) number assigned	CAF
CP54B	Different name/ID number on return; need more information	Name/SSN
CP54E	Different name/ID number on return; need more information	Name/SSN
CP54G	Different name/ID number on return; need more information	Name/SSN
CP54Q	Need updated name/SSN; no response to previous notice	Name/SSN
CP560A	Child assigned an Adoption Taxpayer Identification Number (ATIN)	ATIN
CP560B	One-year extension granted for child’s ATIN	ATIN
CP561A	Child’s ATIN expires in 3 months	ATIN
CP561B	Extension for child’s ATIN expires in 3 months	ATIN
CP561C	Child’s ATIN has expired	ATIN
CP562A	Incomplete Form W-7A; need more information	ATIN
CP562C	Need more information to process extension for child’s ATIN	ATIN
CP563	Need more information to process Form W-7A	ATIN
CP565	Individual Taxpayer Identification Number (ITIN) assigned	ITIN
CP565SP	ITIN assigned (Spanish)	ITIN
CP566	Need more information to process ITIN application	ITIN
CP567	ITIN application rejected	ITIN
CP57	Penalty assessed for insufficient funds	Penalty
CP59	No record of prior tax return(s) being filed	Filing
CP60	Payment erroneously applied; removed from account	Payment
CP601	Balance due (Spanish)	Balance due
CP603	Unpaid balance, no response (Spanish)	Balance due
CP604	Unpaid balance; levy/state tax offset warning (Spanish)	Balance due
CP615I	Past-due amount for prior year taxes; action needed (Spanish)	Balance due
CP616	Reminder that tax payment is due (Spanish)	Balance due
CP618I	Prior tax return(s) missing; final notice (Spanish)	Filing
CP62	Payment applied to account	Payment
CP621	Installment agreement payment overdue (Spanish)	Installment agreement
CP623	Installment agreement defaulted; intent to terminate and levy (Spanish)	Levy
CP63	Holding refund; unfiled returns expected to result in taxes owed	Refund
CP701B	IRS needs more information to process tax return (Spanish)	Identity theft
CP701C	Account flagged for identity theft (Spanish)	Identity theft
CP701S	Identity theft claim received; refund or more information forthcoming (Spanish)	Identity theft
CP71	Reminder of unpaid balance, penalty, and interest owed	Balance due
CP711	Balance due from changes on tax return (Spanish)	Balance due
CP712	Changes made to correct math error (Spanish)	Return error
CP713	Changes made to correct math error; zero balance (Spanish)	Zero balance
CP714	Past-due amount owed (Spanish)	Balance due
CP71A	Reminder of outstanding balance; payment needed to avoid additional penalties	Balance due
CP71C	Tax, penalty, and interest still owed; payment needed to avoid further penalties	Balance due
CP71D	Reminder notice of tax, penalty, and interest owed	Balance due
CP71H	Reminder notice of unpaid SRP balance	Balance due
CP72	Frivolous return identified; no basis in tax law	Frivolous return
CP721	Changes requested for IRA contributions result in a balance due (Spanish)	Balance due
CP721B	Changes requested result in a refund; refund issued in 2–3 weeks (Spanish)	Refund
CP721C	Changes requested result in zero balance (Spanish)	Zero balance
CP721E	Changes requested result in taxes owed (Spanish)	Balance due
CP721I	Changes to return result in additional taxes owed for IRA contributions (Spanish)	Balance due
CP722	Changes requested result in taxes owed (Spanish)	Balance due
CP722E	Changes from recent audit result in taxes owed (Spanish)	Balance due
CP722I	Changes to return result in additional taxes owed for IRA contributions (Spanish)	Balance due
CP74	Form 8862 received; eligibility confirmed for certain tax credits	EITC
CP749	All or part of refund used to pay tax debt (Spanish)	Payment
CP75	Audit of return; further documentation required; may affect EITC and/or dependent credits	EITC
CP759	No record of prior tax return(s) being filed (Spanish)	Filing
CP75A	Audit of return; need to verify EITC, exemptions, and filing status	EITC
CP75C	Banned from claiming EITC due to past violation	EITC
CP75D	Audit of return; need to verify income and withholding; may affect EITC, etc.	EITC
CP76	EITC allowed; refund expected within 8 weeks (if no other tax debts)	EITC
CP77	Intent to levy assets; notice of CDP hearing rights	Levy
CP771	Balance due reminder — tax, penalties, and interest (Spanish)	Balance due
CP772	Balance due reminder — tax, penalties, and interest (Spanish)	Balance due
CP773	Balance due reminder — tax, penalties, and interest (Spanish)	Balance due
CP774	Balance due reminder — tax, penalties, and interest (Spanish)	Balance due
CP79	EITC denied; cannot be claimed until eligibility proven	EITC
CP79A	EITC denied due to recklessness; ineligible for 2 years	EITC
CP79B	EITC denied due to fraud; ineligible for 10 years	EITC
CP80	Payments/credits applied to account, but return is missing	Filing
CP81	Missing return for specific year, refund claim deadline approaching	Filing
CP87A	Duplicate dependent or qualifying child claimed on another return	Duplicate TIN
CP87B	Claimed exemption while being claimed as dependent exemption on another return	Duplicate TIN
CP87C	Same dependent claimed on another return (income exceeds exemption)	Duplicate TIN
CP87D	Dependent on your return also filed jointly; may not qualify for EITC	Duplicate TIN
CP88	Holding refund; unfiled returns and expected tax liability	Filing
CP90	Intent to levy assets; notice of CDP hearing rights	Levy
CP90C	Levy action taken on assets; notice of CDP hearing rights	Levy
CP91	Intent to levy up to 15% of Social Security benefits; notice of CDP hearing rights	Levy
CP92	Levy action taken on state tax refund; notice of CDP hearing rights	Levy
CP94	Restitution-based assessment made per court order	Levy
Letter 0012C	Information needed to reconcile advance payments of Premium Tax Credit (PTC)	General
Letter 0484C	Collection Information Statement requested (433F/433D) or unable to pay/transfer	General
Letter 0549C	Balance due on account paid	General
Letter 0681C	Proposal to pay accepted	General
Letter 0757C	Installment privilege terminated	General
Letter 1961C	Installment agreement for direct debit 433-D	General
Letter 1962C	Installment agreement granted/revised	General
Letter 2257C	Total balance due	General
Letter 2271C	Installment agreement revisions for direct debit	General
Letter 2272C	Installment agreement cannot be considered due to unpaid balance	General
Letter 2273C	Installment agreement granted; terms explained	General
Letter 2357C	Abatement of penalties and interest	General
Letter 2603C	Installment agreement granted; notice of federal tax lien	General
Letter 2604C	Pre-assessed installment agreement	General
Letter 2761C	Request for combat zone service dates	General
Letter 2789C	Taxpayer response to reminder of balance due	General
Letter 2800C	Incorrect W-4 (withholding allowance)	General
Letter 2801C	Not entitled to claim exempt status	General
Letter 2802C	Withholding does not comply with IRS guidelines	General
Letter 2840C	Confirmation of direct debit installment agreement (DDIA)	General
Letter 3030C	Balance due explained; tax and Interest not paid	General
Letter 3127C	Revision or reinstatement of installment agreement	General
Letter 3217C	Installment agreement accepted; terms explained	General
Letter 4281-A	Get Transcript incident; notice of unsuccessful attempt to use taxpayer SSN to access transcripts	General
Letter 4281-B	Get Transcript incident; notice of successful attempt to use taxpayer SSN to access transcripts	General
Letter 4281-C	Notice of data loss/disclosure to potentially impacted individuals	General
Letter 4281-E	Get Transcript incident; primary taxpayer notified of possible SSN disclosure of others on return	General
Letter 4281-F	Get Transcript incident; notification for individuals indirectly related to the accessed account	General
Letter 4281-G	Get Transcript incident; notification that taxpayer’s SSN was used to access transcripts	General
Letter 4458C	Monthly installment payment not received	General
Letter 4883C	Return received; more information needed to process	General
Letter 5071C	Return received; identity verification needed to process	Identity theft
Letter 5591	PTC non-filer letter	General
Letter 5591A	PTC non-filer letter	General
Letter 5596	PTC non-filer letter	General
Letter 5598	Return filed without attaching Form 8962; need to file amended return	General
Letter 5599	Return filed without attaching Form 8962; need to file amended return	General
Letter 5600C	May have overpaid SRP on 2014 return	General
Letter 5821	Need to renew ITIN to file a return	General
Letter 5821 (SP)	Need to renew ITIN to file a return (Spanish)	General
Letter 5858	Form 1095-A received; must reconcile PTC	General
Letter 5858 (SP)	Form 1095-A received; must reconcile PTC (Spanish)	General
Letter 5862	Form 1095-A received; must reconcile PTC	General
Letter 5862 (SP)	Form 1095-A received; must reconcile PTC (Spanish)	General
LP47	Request for assistance in locating taxpayer (for employers)	Address update
LP59	Previous levy notice received; no response	Levy
LP61	Need information about current or former employee	Taxpayer info request
LP62	Information request about taxpayer to resolve tax matter	Taxpayer info request
LP64	Request for assistance in locating taxpayer	Locate taxpayer
LP68	Release of levy notice	Levy
LT11	Notice of intent to levy for overdue taxes	Levy
LT14	Past-due taxes; unable to reach taxpayer	Balance due
LT16	Enforcement action may be taken to collect taxes	Balance due
LT18	No response to previous requests for overdue return	Balance due
LT24	Received installment agreement offer; more information needed	Balance due
LT26	No response to previously requested information for a specific tax period	Information request
LT27	Need to file Form 433-F for payment plan	Installment agreement
LT33	Payment received, but outstanding balance remains	Balance due
LT39	Legal requirement to issue reminder of overdue taxes	Balance due
LT40	Trying to collect taxes; may contact others to verify info	Balance due
LT41	Trying to collect unfiled returns or SRP; may contact others to verify info	Balance due
LT73	Notice of levy to collect unpaid federal employment taxes	Employment tax
LT75	Federal tax unpaid; levy issued to collect	Levy
SP64	Request for assistance in locating taxpayer (Spanish)	Locate taxpayer
ST11	Notice of intent to levy for overdue taxes (Spanish)	Levy
ST14	Balance due on unpaid taxes (Spanish)	Balance due
ST16	Enforcement action may be taken to collect taxes (Spanish)	Balance due
ST18	Enforcement action may be taken to collect taxes (Spanish)	Balance due
ST24	Received installment agreement offer; more information needed (Spanish)	Balance due
ST26	No response to previously requested information for a specific tax period (Spanish)	Information request
ST27	Need to file Form 433-F for payment plan (Spanish)	Installment agreement
ST33	Payment received, but outstanding balance remains (Spanish)	Balance due
ST39	Legal requirement to issue reminder of overdue taxes (Spanish)	Balance due
ST40	Trying to collect taxes; may contact others to verify info (Spanish)	Balance due
ST41	Trying to collect unfiled returns or SRP; may contact others to verify info (Spanish)	Balance due
ST73	Notice of levy to collect unpaid federal employment taxes (Spanish)	Employment tax
ST75	Federal tax unpaid; levy issued to collect (Spanish)	Levy

Disclaimer: This post provides general information and should not be considered tax advice. Consult a qualified tax professional for guidance tailored to your specific tax situation.