To amend Form 1065, a partnership files either a corrected Form 1065 marked as amended (electronically) or Form 1065-X (on paper) if it is not subject to the Bipartisan Budget Act centralized audit regime, or an Administrative Adjustment Request if it is. That single BBA question drives the forms you use, who signs them, and who ends up paying any additional tax. Before you go down either road, check whether the original filing deadline, including extensions, has actually passed.
Check the Deadline Before You Amend
If the original due date (with extensions) is still open, you don’t need to amend at all. You file a superseding return, which completely replaces the original. The IRS treats the corrected version as the original return for all purposes.1Taxpayer Advocate Service. What to Know About Superseding Tax Returns and How It Could Benefit You
That matters because certain tax elections must be made on a timely filed original return and become irrevocable once the deadline passes. A superseding return keeps those elections in play. An amended return filed after the deadline cannot.
To file electronically, submit a complete corrected Form 1065 and select the superseding return designation in your tax software. On paper, there is no separate checkbox; you file a complete replacement Form 1065 before the extended due date.2Internal Revenue Service. Amended and Superseding Corporate Returns
Once that window closes, any correction becomes a formal amended return or Administrative Adjustment Request. Common triggers: misclassified income (guaranteed payments reported as distributions, for example), incorrect allocation of liabilities, errors in depreciation or Section 179 amounts, and adjustments flowing from a lower-tier entity audit. Any change that alters Schedule K or any partner’s Schedule K-1 requires a formal correction.
Determine Whether BBA Applies
The single most important question is whether the partnership falls under the Bipartisan Budget Act centralized audit regime. BBA applies to all partnerships for tax years beginning after December 31, 2017, unless the partnership validly elected out.3Internal Revenue Service. BBA Centralized Partnership Audit Regime
A partnership can elect out only if it had 100 or fewer partners during the tax year and every partner was an “eligible partner” at all times during that year. Eligible partners include individuals, C corporations, foreign entities that would be C corporations if domestic, S corporations, and estates of deceased partners.4Internal Revenue Service. Elect Out of the Centralized Partnership Audit Regime Trusts and other partnerships do not qualify. One trust partner is enough to disqualify the election.
If the partnership elected out, or the tax year predates 2018, follow the non-BBA process. Otherwise, you file an Administrative Adjustment Request.
Amending a Non-BBA Partnership Return
Non-BBA partnerships have two filing options, and electronic is the faster and more reliable path.
Electronic Filing
Prepare a complete corrected Form 1065 with all schedules and attachments, select the “Amended Return” checkbox, and attach an Amended Return Statement explaining each change. Include corrected Schedules K-1 for every affected partner.5Internal Revenue Service. Guidance for Amended Partnership Returns The return must be complete, not just the changed items. Any form or schedule that changed, or that supports a change, must be included.
Paper Filing With Form 1065-X
Partnerships that don’t file electronically use Form 1065-X, Amended Return or Administrative Adjustment Request.6Internal Revenue Service. About Form 1065-X, Amended Return or Administrative Adjustment Request (AAR) The form provides a side-by-side comparison showing original amounts, the net change for each line item, and the corrected amounts. Focus only on lines that need correction.
The net change column captures the financial impact of each adjustment. An increase in expenses creates a negative adjustment to income; an increase in revenue creates a positive one. These flow through to ordinary business income on Line 22, which in turn affects every partner’s distributive share.
Part III requires a detailed explanation of every change. Vague descriptions trigger IRS correspondence and delay processing. If the correction involves a change to a tax election, reference the specific code section and the date the election was made. Attach all supporting documentation, including revised depreciation schedules or corrected vendor records.
Mail the signed Form 1065-X with all attachments, including corrected Schedules K-1 for every affected partner, to the IRS service center where the original return was filed. The correct address depends on the partnership’s principal place of business. Send everything by certified mail with return receipt requested to establish a clear filing date. Missing K-1s will cause the IRS to reject or significantly delay the submission.
Filing an Administrative Adjustment Request for a BBA Partnership
Under BBA, only the Partnership Representative has authority to file an AAR. The PR’s decisions bind all partners, including the choice to pay at the entity level or push the adjustments out to the reviewed-year partners.
Electronic Filing
To e-file an AAR, file a corrected Form 1065 with box G(5) (“Amended return”) checked, along with Form 8082, Notice of Inconsistent Treatment or Administrative Adjustment Request.7Internal Revenue Service. File an Administrative Adjustment Request for a BBA Partnership If the partnership is making a push-out election or the AAR contains adjustments that don’t result in an imputed underpayment, also include Form 8985 (Pass-Through Statement transmittal) and Forms 8986 (showing each partner’s share of adjustments).
Paper Filing
For paper filing, the Partnership Representative files Form 1065-X instead of the Form 1065 and Form 8082 combination used for e-filing.7Internal Revenue Service. File an Administrative Adjustment Request for a BBA Partnership The same additional forms (8985, 8986) apply when making a push-out election.
Who Pays Under BBA: Imputed Underpayment or Push-Out
When a BBA partnership files an AAR that increases the aggregate tax liability, the default outcome is that the partnership itself pays the resulting “imputed underpayment” at the entity level. The tax is collected from the partnership, not from individual partners.
The imputed underpayment is calculated by netting all adjustments for the reviewed year and multiplying the net positive adjustment by the highest tax rate in effect for that year under IRC Section 1 (for individuals) or Section 11 (for corporations).8Office of the Law Revision Counsel. 26 USC 6225 – Partnership Adjustment by Secretary For most partnerships, that means the 37 percent individual rate applies to the entire adjustment, regardless of any partner’s actual bracket.
The partnership can request modification to reduce the amount. Options include applying lower rates to specific income types like capital gains, accounting for tax-exempt partners’ shares, or reflecting amended returns already filed by partners. If the partnership pays the imputed underpayment, partners generally don’t need to amend their personal returns for that reviewed year. The payment is treated as a non-deductible expenditure that reduces partners’ capital accounts.
Interest on the imputed underpayment runs from the day after the due date of the partnership return for the reviewed year until the earlier of the payment date or the due date of the return for the adjustment year.9eCFR. 26 CFR 301.6233(a)-1 – Interest and Penalties Determined From Imputed Underpayment For a correction going back two or three years, that interest accumulates quickly.
The Push-Out Election
Instead of paying at the entity level, the partnership can elect to push the adjustments out to the partners who were actually in the partnership during the reviewed year. The election is made at the time the AAR is filed and is irrevocable. Include Form 8985 and Forms 8986 with the submission.7Internal Revenue Service. File an Administrative Adjustment Request for a BBA Partnership
Each reviewed-year partner receives a Form 8986 showing their share of the adjustments. The partner reports and pays the resulting tax on their return for the adjustment year (the year the AAR was filed), not by amending the reviewed-year return. Interest and penalties flow to the partners as well.
The push-out election often makes sense when partners have lower effective tax rates than the 37 percent applied to imputed underpayments, or when tax-exempt partners hold a large share. The math is a straight comparison: entity-level imputed underpayment plus interest versus the aggregate tax partners would owe at their individual rates.
The Three-Year Deadline
A partnership can file an amended return or AAR within three years of the later of: the date the partnership return was actually filed, or the last day for filing that return, not counting extensions.10eCFR. 26 CFR 301.6227-1 – Administrative Adjustment Request by Partnership A partnership that filed its 2024 return on February 15, 2025, when the due date was March 15, 2025, has until March 15, 2028. An early return never starts the clock before the due date.
There is a separate cutoff. Once the IRS mails a Notice of Administrative Proceeding for a tax year, the partnership can no longer file an AAR for that year. The IRS does not have to warn you one is coming. If you know a correction is needed, file.
Corrected Schedules K-1 and Partner Obligations
Every amended return or AAR that changes any partner’s Schedule K-1 triggers a mandatory notification. The partnership must furnish corrected Schedules K-1 to all affected partners, clearly marked as “Amended” or “Corrected.”11Office of the Law Revision Counsel. 26 USC 6031 – Return of Partnership Income
For non-BBA partnerships, and for BBA partnerships that made the push-out election, partners receiving corrected K-1s generally need to file amended individual returns (Form 1040-X) or report the adjustments on their current-year return, depending on the method used. Under IRC Section 6222, partners must treat partnership-related items consistently with the partnership’s return. An underpayment resulting from inconsistent treatment is assessed as a math error, which means no deficiency notice and no opportunity to petition Tax Court before paying.12Office of the Law Revision Counsel. 26 USC 6222 – Partner’s Return Must Be Consistent With Partnership Return
A partner who believes the partnership reported an item incorrectly can file Form 8082 to notify the IRS of the inconsistent treatment, preserving the right to use a different figure while avoiding the automatic math-error assessment. For the partnership doing the amending, the practical point is to get corrected K-1s out promptly so partners can meet their own filing obligations.
State Filings
A federal amendment does not take care of the state side. Most states require partnerships to report federal changes within a set window after the federal correction is finalized, often somewhere between 60 and 180 days. Some states require a separate amended state partnership return; others accept a copy of the federal filing with a cover letter. Check your state’s rule promptly, because missing it can trigger separate penalties even when the federal filing was timely.
Penalties and Interest Exposure
Filing an amendment that increases reported income can expose partners, or the partnership under BBA, to accuracy-related penalties. The standard accuracy-related penalty for negligence or substantial understatement is 20 percent of the underpayment attributable to the error. For a gross valuation misstatement, the penalty doubles to 40 percent.
The reasonable cause defense applies. A partnership that can demonstrate it had reasonable cause for the original error and acted in good faith avoids the penalty. Voluntary self-correction through an amended return or AAR generally looks better to the IRS than corrections discovered during an audit, though filing an amendment does not guarantee relief.
For BBA partnerships paying an imputed underpayment, interest begins accruing the day after the due date of the original return for the reviewed year.9eCFR. 26 CFR 301.6233(a)-1 – Interest and Penalties Determined From Imputed Underpayment Even a routine correction for a two-year-old return can carry meaningful interest, which is why the choice between paying at the entity level and pushing out to partners is an economic decision as much as a procedural one.