IRS Form 3870, Request for Adjustment, is an internal IRS document that Revenue Officers, examiners, and other IRS personnel prepare to process changes to a taxpayer’s account. You do not fill it out or submit it yourself, and it is not available for download on irs.gov.1Internal Revenue Service. Internal Revenue Manual 5.1.15 – Abatements, Reconsiderations and Adjustments To get an adjustment made, you file a different form depending on what you need corrected, and IRS staff use Form 3870 behind the scenes to post the change.
Who Prepares Form 3870
Form 3870 lives inside the IRS’s internal case management system. Field Collection employees prepare it, along with supporting documentation, whenever an account needs a correction, credit transfer, penalty abatement, or other adjustment.1Internal Revenue Service. Internal Revenue Manual 5.1.15 – Abatements, Reconsiderations and Adjustments The IRS treats an adjustment as an action taken on a tax module to correct it through the Integrated Data Retrieval System, and Revenue Officers use Form 3870 for identity theft corrections, duplicate return abatements, and substitute-for-return assessments, among other actions.
Examiners also complete Form 3870 when processing adjusted employment tax returns. If you file a Form 941-X to correct a quarterly payroll return, for instance, the examiner prepares a partial Form 3870 to route the credit transfer.2Internal Revenue Service. Internal Revenue Manual 4.23.13 – Adjusted Returns, Abatements and Claims
In limited situations, a taxpayer may be asked to sign a Form 3870, but only when they have not already submitted a separate signed written request for reconsideration. Even then, you don’t prepare the form.
The Form You Actually File
The adjustment starts with you. What you submit depends on the correction you need.
Amended Returns: Form 1040-X
To change income, deductions, credits, or filing status on a return you already filed, submit Form 1040-X, Amended U.S. Individual Income Tax Return. An amended return generally requires a signed, complete submission with all supporting schedules, even for items that haven’t changed. Once the IRS processes the 1040-X, internal personnel may use Form 3870 to carry out the resulting account adjustments.3Internal Revenue Service. Internal Revenue Manual 21.5.2 – Adjustment Guidelines
Penalty or Interest Abatement: Form 843
To ask the IRS to remove a penalty or abate interest caused by IRS error or delay, file Form 843, Claim for Refund and Request for Abatement. Interest will be abated only when the charge resulted from an unreasonable error or delay in performing a managerial or ministerial act and you did not cause any significant part of the problem.4Internal Revenue Service. Instructions for Form 843
Penalty abatement based on reasonable cause can sometimes be requested verbally by phone. Interest abatement always requires a written submission. Form 843 or a signed letter with the same information (your name, taxpayer identification number, the period in question, the reason for the request, and a signature under penalties of perjury) satisfies that requirement.3Internal Revenue Service. Internal Revenue Manual 21.5.2 – Adjustment Guidelines
Audit Reconsideration: Form 12661 or a Written Request
If you disagree with a completed audit assessment and have documentation the IRS did not review during the original examination, you can request an audit reconsideration. To qualify, the assessment must remain unpaid, or the IRS must have reversed credits you dispute, and you must provide information not previously considered.5Internal Revenue Service. Internal Revenue Manual 4.13.1 – Examination Audit Reconsideration Process
Submit Form 12661, Disputed Issue Verification, or your own letter explaining each adjustment you contest. Include supporting documents such as receipts, bank statements, or Forms 1099 that you didn’t provide before. You can send materials through the Document Upload Tool at irs.gov/examreply, by fax, or by mail to the office that handled the audit.6Internal Revenue Service. Audit Reconsideration Process for Correspondence Examination Once the reconsideration unit accepts the request, the Revenue Officer or examiner handling the case prepares Form 3870 internally to process any resulting account changes.
CP2000 Notices
A CP2000 notice means the IRS found a mismatch between what you reported and information from third parties such as employers or banks. If you agree with the proposed changes, sign and return the response form included with the notice. If the notice is correct but you also have unreported income or additional credits to claim, file Form 1040-X with “CP2000” written at the top.7Internal Revenue Service. Understanding Your CP2000 Series Notice Ignoring the notice leads to a bill and continued interest.
Agreeing With Audit Findings: Form 870
When an audit concludes, the IRS sends Form 4549, Report of Income Tax Examination Changes, laying out the proposed adjustments, along with Form 886-A explaining the reasons.8Internal Revenue Service. Audits by Mail – What to Do If you agree, you sign Form 870, Waiver of Restrictions on Assessment and Collection. Signing consents to immediate assessment of any additional tax owed and accepts any overassessment the audit identified.9Internal Revenue Service. Form 870 – Waiver of Restrictions on Assessment and Collection of Deficiency
Signing Form 870 gives up your right to contest those years in Tax Court. You can still file a refund claim later after paying the tax, and the IRS can still determine you owe more, but the Tax Court door closes. The IRS will treat a signed Form 870 as a valid refund claim for any overpayment it shows, if it’s filed within the period allowed by law.9Internal Revenue Service. Form 870 – Waiver of Restrictions on Assessment and Collection of Deficiency After you sign, examination staff prepare the internal paperwork, including Form 3870, to post the adjustments.
Deadlines for Refund and Credit Claims
An adjustment that produces a refund or credit has to fall within the statute of limitations. You have either three years from the date you filed the return or two years from the date you paid the tax, whichever period expires later.10Office of the Law Revision Counsel. 26 U.S. Code 6511 – Limitations on Credit or Refund If you never filed a return, the window shrinks to two years from the date of payment. Once these deadlines pass, the IRS cannot issue a refund regardless of the merits.
A lookback rule limits the refund amount to taxes paid within the applicable two- or three-year period. Withholding and estimated tax payments are treated as paid on the original due date of the return, typically April 15. So an adjustment involving a refund for a tax year more than three years old may already be out of reach in whole or in part.
Authorizing a Representative
You can authorize a tax professional to handle the adjustment process on your behalf by filing Form 2848, Power of Attorney and Declaration of Representative. The authorization must specify the exact tax matters, form numbers, and periods covered. General references like “all years” or “all taxes” cause the IRS to reject the power of attorney.11Internal Revenue Service. Instructions for Form 2848 Once the authorization is on file, your representative can communicate with the IRS, submit documentation, sign agreements, and receive confidential tax information for the specified matters. A representative cannot endorse or negotiate a refund check or direct electronic payment into their own account.
What to Expect After You Submit
Processing times vary. A straightforward amended return filed electronically may process within about three weeks; complex adjustments involving examinations, penalty abatements, or credit transfers routinely take several months. The IRS posts current timelines on its website.
When the review finishes, you receive written notification. An agreed examination typically produces an account adjustment notice confirming the changes. A denial letter explains the reason and, for audit reconsiderations, often outlines what additional documentation would be needed to try again. If you’re mailing a request near a statute of limitations deadline, use certified mail with return receipt so you have a clear record of when the IRS received it.