Understanding Combined Notices for Multiple Tax Years

Quick overview

Combined notices are IRS letters or notices that group related issues or balances that span more than one tax year into a single communication. These notices can speed up resolution when the same transaction, employer reporting, or information mismatch affects multiple returns. If you receive one, treat it as actionable — it summarizes multiple problems in one place and often includes response instructions, balance details, and appeal information.

Author note: As a CPA and CFP® with more than 15 years helping individuals and small businesses navigate IRS correspondence, I’ve found that early organization and a calm, methodical response usually avoids added penalties and interest.

Background: Why the IRS started using combined notices

Historically, the IRS sent separate notices for each tax year. That helped in simple cases but caused confusion when the same issue — such as underreported income, unfiled forms, or payroll tax errors — affected multiple years. To reduce taxpayer burden and improve case management, the IRS began consolidating related items into combined notices. The goal is clearer communication and a single point of contact for issues that are effectively the same problem repeated across tax years.

The IRS’s guidance on notices and letters encourages taxpayers to read their correspondence carefully and follow the instructions (see IRS guidance: “Understanding Your IRS Notice or Letter”).

External reference: IRS — Understanding Your IRS Notice or Letter: https://www.irs.gov/individuals/understanding-your-irs-notice-or-letter

How combined notices work in practice

A combined notice typically includes:

• A headline or notice ID describing the subject (for example, proposed changes to reported income or a balance due).
• A list of the affected tax years with the IRS’s proposed changes and resulting balances.
• A clear explanation of why the IRS thinks a change is appropriate (e.g., mismatch between third-party information such as W-2s/1099s and filed returns).
• Instructions for how to respond, a deadline, and payment or appeal options.

Common triggers for combined notices:

• IRS automated matching systems (e.g., underreporter or information matching programs) identify the same issue in multiple years.
• Related changes submitted by an employer or payer (e.g., corrected W-2 or 1099) affect several years.
• Audit or review processes that uncover a recurring error in accounting, filing status, or payroll reporting.

What to expect when you receive one:

1. Read the notice header and the list of affected tax years.
2. Compare the IRS’s figures to your copies of the returns and to third-party forms (W-2, 1099, Form 1095, payroll reports).
3. Decide whether to agree, dispute, or request more time. The notice will normally list response instructions and deadlines.

If the notice proposes changes to a return (for example, a proposed increase in income or disallowance of a deduction), you may receive a notice type such as CP2001 (proposed change). For guidance on that kind of message, see our article “Decoding CP2001: Proposed Notice of Change to Your Return.” (internal link)

Real-world examples (anonymized)

• Example 1 — Individual underreported freelance income: A taxpayer received corrected 1099s for three consecutive tax years. The IRS issued a combined notice proposing additional income across all three years. By supplying bank records and amended returns for the affected years, we limited penalties and set up a manageable payment plan.

• Example 2 — Small business payroll mismatch: A small business owner discovered that payroll deposits did not match what was reported on employer returns for two tax years. The IRS issued a combined notice for the employer’s share of employment taxes across both years. We worked with a payroll specialist, corrected the reports, and negotiated an installment agreement to address cashflow concerns.

These examples illustrate that combined notices are often practical: they consolidate fixes and make it easier to negotiate a single resolution method (payment plan, amended filings, or appeals) instead of repeating the same process for each year.

Who is affected and when you’re likely to get a combined notice

Anyone can receive a combined notice — individuals, S corporations, partnerships, and employers. Typical scenarios include:

• Repeated underreporting of the same income type (e.g., contractor pay recorded on 1099s)
• Corrected third-party reporting that affects several past returns
• Patterned math or filing errors across years

If you received multiple notices that look similar or if several years are listed in one communication, it’s a combined notice. If you’re unsure, compare the IRS mail piece to examples and explanations in our guide “Understanding IRS Correspondence: Letters, Notices, and Bills.” (internal link)

Step-by-step actions to take immediately (practical checklist)

1. Do not ignore the notice. Note the deadline and any appeal window.
2. Read every page. Identify the tax years impacted and the IRS’s proposed changes.
3. Pull the relevant tax returns and third-party documents (W-2s, 1099s, payroll ledgers, amended forms).
4. Recalculate the affected items or consult a tax professional to determine whether the IRS numbers are correct.
5. If you agree, follow the payment or agreement instructions. If you disagree, prepare a clear written response and supporting documentation.
6. If you need more time, call the IRS using the phone number on the notice or request a reasonable extension — don’t assume you’ll have extra time without requesting it.
7. Consider whether the case is better handled by a tax pro; complex multi-year issues or potential penalties usually benefit from professional input.

For common scenarios involving balances and payment options, our “Responding to a Balance Due Notice: Practical Steps” article covers practical next steps and negotiating installment agreements. (internal link)

How to dispute or appeal (overview)

If you disagree with the IRS’s proposed change, reply in writing with copies of supporting documents. Some notices allow administrative appeals within the IRS; others (for example, a Notice of Deficiency, CP3219A) open up court options — typically a 90-day window to petition the U.S. Tax Court. See our guide on preparing a protest for a Notice of Deficiency for details and templates. (internal link)

The IRS also describes procedures for responding to notices and requesting an appeal in its public guidance (see IRS: Understanding Your IRS Notice or Letter).

Professional tips and strategies I use with clients

• Start with organization: create a single file for the case containing the IRS notice, each year’s tax return, and third-party forms.
• Address the most recent year first if the pattern suggests a continuing problem; that often reduces future exposure.
• Use amended returns when appropriate, but be mindful that amendments can reopen other years in some cases; ask a tax professional before filing an amended return across multiple years.
• When negotiating payment, propose realistic monthly amounts and document your household or business cash flow. The IRS prefers a feasible plan.
• If penalties are significant, request abatement for reasonable cause; common accepted reasons include natural disasters, serious illness, or reliance on incorrect written advice from the IRS.

Common mistakes and misconceptions

• Mistake: Assuming combined means “final.” Many combined notices propose changes and allow responses. Read the instructions and deadlines carefully.
• Mistake: Responding without supporting documentation. A strong documented response reduces the chance of default assessments.
• Misconception: All combined notices are the same. They can range from automated information-matching letters to results of field examinations. The response process depends on the notice type.

Frequently asked questions

Q: Is a combined notice the same as an audit?
A: Not always. A combined notice often results from automated or centralized processes. Some combined notices reflect audit findings, while others are informational or proposed adjustments. The notice will typically state if it’s part of an audit.

Q: Can the IRS collect for all years at once?
A: Yes. The balance shown may reflect total amounts for all affected years. The IRS may request payment in full, propose an installment agreement, or levy if collection action progresses.

Q: How long do I have to respond?
A: Response windows vary by notice type. Some proposed-change notices have a 30-day or 60-day response window; a Notice of Deficiency typically allows 90 days to petition Tax Court. Check the specific notice and act before the deadline.

Practical resources and next steps

• Read the IRS guidance “Understanding Your IRS Notice or Letter” for general rules and contact options: https://www.irs.gov/individuals/understanding-your-irs-notice-or-letter
• If the notice involves proposed changes (e.g., CP2001) or income mismatches, review our detailed article “Decoding CP2001: Proposed Notice of Change to Your Return.” (internal link)
• For collection and payment options, see “Responding to a Balance Due Notice: Practical Steps.” (internal link)

Professional disclaimer

This article is educational and does not replace personalized tax advice. Tax situations vary. Consult a qualified tax professional or attorney before taking action that affects your tax liability.

Authoritative sources

• IRS — Understanding Your IRS Notice or Letter (2025) https://www.irs.gov/individuals/understanding-your-irs-notice-or-letter
• IRS — Notices and Bills, general guidance (see IRS.gov)

If you want, I can review a redacted copy of your notice and outline next steps or a response template. Contact a CPA or tax attorney for case-specific guidance.