IRS Notice Decoder Library

Letters offering an appeal opportunity
Explains IRS letters and notices that give taxpayers the right to request an appeal or hearing before certain IRS actions become final.

Practitioner tip: Calendar the response deadline immediately and confirm whether the notice preserves appeal, Collection Due Process or other review rights before advising the client to agree or pay.

Practitioner tip: Start with the notice or letter number in the upper corner, then reconcile the notice against the filed return, account transcript and payment history before calling the IRS.

Understanding your LT11 notice or letter 1058
Final notice that the IRS intends to levy property or rights to property and explains the taxpayer’s Collection Due Process hearing rights.

Practitioner tip: Treat this as a hard-deadline collection notice; evaluate Form 12153, payment alternatives and whether the underlying liability can still be challenged.

Understanding your LT73 notice
IRS collection notice related to unpaid taxes that explains required next steps and available resolution options.

Practitioner tip: Pull current transcripts before responding because collection notices can lag behind posted payments, pending adjustments or newly established installment agreements.

Understanding Letter 105-C, Disallowance of the Employee Retention Credit
Letter 105-C is the legal notice that the IRS has disallowed, or denied, the ERC claimed either as a refund or as a reduction of the tax owed for the tax period.

Practitioner tip: Treat a Letter 105-C as a formal denial of the entire ERC claim and immediately calendar the two-year deadline to file a refund suit. If you disagree with the IRS determination, promptly assemble documentation supporting eligibility, claim timeliness, and the credit amount, and pursue administrative review without losing sight of the litigation deadline. Appeals review generally does not suspend the two-year period. The 2-year period can be extended in writing between the IRS and the taxpayer. The IRS uses Form 907, Agreement to Extend the Time to Bring Suit, to extend this time period. Form 907 must be countersigned before expiration of the 2-year period to extend the refund statute.

If you receive Letter 106-C about the Employee Retention Credit
Letter 106-C, Claim Partially Disallowed, is the legal notice that the IRS partially disallowed, or denied, the claim for the tax period stated in the letter.

Practitioner tip: Carefully reconcile the IRS adjustments against your original ERC claim to identify exactly which quarters, wages, or eligibility positions were disallowed. Focus your response on the disputed amounts and preserve support for both the allowed and disallowed portions. Even when only part of the claim is denied, the two-year deadline for challenging the disallowed portion remains a critical consideration. The 2-year period can be extended in writing between the IRS and the taxpayer. The IRS uses Form 907 to extend this time period. Form 907 must be countersigned before expiration of the 2-year period to extend the refund statute.

Understanding your letter 4883C
Identity verification letter asking the taxpayer to confirm their identity before the IRS continues processing the return.

Practitioner tip: Have the taxpayer complete verification directly and keep proof of completion; representatives usually cannot complete identity verification for the taxpayer.

Notices offering an appeal opportunity
Explains IRS letters and notices that give taxpayers the right to request an appeal or hearing before certain IRS actions become final.

Practitioner tip: Identify the appeal route and deadline first; rights can be lost even when the underlying tax issue is still fixable.

Understanding your IRS notice
General IRS guide for identifying why a notice or letter was sent, what changed, and what action may be needed.

Practitioner tip: Use the notice number as the triage key and compare the IRS position to the return, transcripts, source documents and client payment records.

Understanding your CP09 notice
Notice that the taxpayer may qualify for the Earned Income Credit and should review eligibility and respond if claiming it.

Practitioner tip: Confirm qualifying child, residency and earned income support before submitting Form 15111; do not claim the credit simply because the IRS identified possible eligibility.

Understanding your CP10 notice
Notice that the IRS changed the return, reducing the estimated tax payment credited to the next tax year.

Practitioner tip: Check whether the reduced carryforward affects current-year estimated tax safe harbors and client payment planning.

Understanding your CP11 notice
Notice that the IRS corrected one or more errors on the return and the correction resulted in a balance due.

Practitioner tip: Review the math error authority and response deadline quickly; if the IRS correction is wrong, request abatement or reversal in writing with support.

Understanding your CP12 notice
Notice that the IRS corrected one or more errors on the return, changing the refund amount.

Practitioner tip: Compare the revised refund to the return and transcript before amending; many issues are resolved by disputing the notice rather than filing Form 1040-X.

Understanding your CP13 notice
Notice that the IRS corrected one or more errors on the return, but the correction did not change the tax owed or refund due.

Practitioner tip: Even with no dollar impact, update the client file and carryforward schedules so the same discrepancy does not repeat next year.

Understanding your CP14 notice
First notice that the IRS processed the return and shows a balance due.

Practitioner tip: Verify posted payments and extensions before recommending payment; recent payments may not have posted when the notice generated.

Understanding your CP16 notice
Notice that the IRS adjusted the return and used all or part of the refund to pay another tax debt.

Practitioner tip: Trace the offset to the specific tax period and module; the correct response may involve the other year, not the year shown on the return.

Understanding your CP21B notice
Notice that the IRS made requested changes to the return and the adjustment resulted in a refund.

Practitioner tip: Confirm the refund amount and interest computation, then verify whether any offset occurred before closing the client matter.

Understanding your CP22A notice
Notice that the IRS made changes to the return and the adjustment resulted in a balance due.

Practitioner tip: Determine whether the adjustment came from taxpayer-requested changes, IRS processing or examination activity before deciding whether to pay, dispute or amend.

Understanding your CP23 notice
Notice that estimated tax payments claimed on the return do not match IRS records, creating a balance due or change.

Practitioner tip: Reconcile by payment date, amount, tax year and taxpayer identification number; misapplied estimates often require payment tracing rather than return changes.

Understanding your CP32A notice
Notice that a refund check expired before it was cashed and the taxpayer must call the IRS to request a replacement check.

Practitioner tip: Confirm the current mailing address before the replacement is issued and check for offsets that may reduce or eliminate the reissued refund.

Understanding your CP45 notice
Notice that the IRS could not apply an overpayment to next year’s estimated tax as requested.

Practitioner tip: Rebuild the estimated tax worksheet after the notice because the expected credit may not be available for the next period.

Understanding your CP49 notice
Notice that the IRS used all or part of a refund to pay an existing federal tax debt.

Practitioner tip: Review all open balances and spouse allocation issues; injured spouse relief may be relevant when the offset relates to the other spouse’s liability.

Understanding your CP53E notice
Notice that a refund could not be issued by direct deposit because bank information was missing, invalid or rejected, and the taxpayer may need to update deposit information.

Practitioner tip: Manage expectations around paper-check timing and confirm the mailing address; do not assume the refund is lost just because the deposit failed.

Understanding your CP54B notice
Notice that the name or taxpayer identification number on the return does not match IRS records and more information is needed before the refund can be issued.

Practitioner tip: Compare the return to Social Security Administration records, ITIN documentation and prior-year filings before resubmitting information.

Understanding your CP59 notice
Notice that the IRS has no record of a required prior-year personal tax return and asks the taxpayer to file or explain why filing is not required.

Practitioner tip: Confirm filing status, income thresholds and any extension or e-file rejection history before filing a substitute or duplicate return.

Understanding your CP75 notice
Audit notice requesting documentation to verify Earned Income Credit or other refundable credits while the related refund amount is held.

Practitioner tip: Build a complete documentation packet for residency, relationship, income and support issues; piecemeal responses often prolong the refund hold.

Understanding your CP79 notice
Notice that before claiming certain credits again, the taxpayer must show eligibility for the previously audited year, often by filing Form 8862 with a future return.

Practitioner tip: Flag the client’s next filing season file so Form 8862 and supporting eligibility documentation are addressed before the return is filed.

Understanding your CP90 notice
Final notice that the IRS intends to levy certain assets for unpaid taxes and explains Collection Due Process hearing rights.

Practitioner tip: Prioritize the Collection Due Process deadline and evaluate Form 12153, installment agreement, currently not collectible status or offer options before levy action proceeds.

Understanding your CP92 notice
Notice that the IRS levied a state tax refund for unpaid taxes and explains the taxpayer’s right to request a Collection Due Process hearing.

Practitioner tip: Confirm whether the levy has already occurred and preserve hearing rights if available; the strategy may differ once the state refund has been applied.

Understanding your CP161 notice
Business tax notice showing a balance due, no balance due or overpayment after the IRS processed a return or account adjustment.

Practitioner tip: Check payroll, excise or entity account modules carefully; business notices may involve deposit penalties or periods not obvious from the client’s summary.

Understanding your CP242 notice
Notice related to changes or adjustments on the taxpayer’s account that may affect the amount owed or credited.

Practitioner tip: Pull the account transcript to identify the transaction codes driving the adjustment before advising the client on next steps.

Understanding your CP297 notice
Final notice of intent to levy and notice of hearing rights for unpaid taxes, often used in collection cases involving certain federal payments.

Practitioner tip: Treat it like a final levy notice: preserve CDP rights, document financial hardship where applicable and explore collection alternatives immediately.

Understanding your CP501 notice
Reminder notice that the IRS still shows a balance due and payment or other resolution is needed.

Practitioner tip: This is often a good point to resolve the account before collection escalates; verify the balance and set up a payment strategy early.

Understanding your CP503 notice
Second reminder that the IRS has not received payment for a balance due and collection activity may continue if unresolved.

Practitioner tip: Reconfirm the account transcript and act before the case moves to stronger collection language or levy-warning notices.

Understanding your CP504 notice
Notice of intent to levy state tax refunds or other property if the taxpayer does not resolve the unpaid balance.

Practitioner tip: Do not treat this as a routine bill; confirm levy risk, discuss payment alternatives and watch for the next notice that may trigger broader CDP rights.

Understanding your CP523 notice
Notice that an installment agreement may default or has defaulted because required payments or terms were not met.

Practitioner tip: Identify the default trigger—missed payment, new balance or unfiled return—and cure it quickly to preserve or reinstate the agreement.

Understanding your CP531 notice
Notice related to a terminated or defaulted payment arrangement that explains what must be done to avoid further collection action.

Practitioner tip: Review compliance for all filing and payment obligations; reinstatement often depends on resolving current-year filing or deposit issues first.

Understanding your CP2000 notice
Proposed adjustment notice sent when income, payment or credit information reported to the IRS does not match the filed return.

Practitioner tip: Remember this is proposed, not assessed; reconcile every information document and respond with a clear agree, partially agree or disagree position by the deadline.