What Is IRS Form 6251?
IRS Form 6251, titled Alternative Minimum Tax (AMT) for Individuals, is used to determine whether you owe the Alternative Minimum Tax (AMT) and to calculate the amount due if it applies.
The AMT is a separate tax calculation designed to ensure certain taxpayers pay a minimum level of tax when deductions, credits, or exemptions significantly reduce regular tax liability.
What Is Form 6251 Used For?
Form 6251 is used to:
- Calculate whether the Alternative Minimum Tax applies
- Recalculate taxable income using AMT rules
- Add back or adjust certain deductions and exclusions
- Determine if AMT is owed in addition to regular income tax
If the AMT calculation is higher than your regular tax, you generally pay the AMT amount.
Read More: Alternative Minimum Tax (AMT): What It Is, Who Pays It, and Why 2025–2026 Could Change Everything
When Should You File Form 6251?
You may need to file Form 6251 if:
- You claim deductions or credits affected by AMT rules
- You have income from stock options, incentive stock options (ISOs), or certain investments
- You have large itemized deductions or preference items
- Tax software or the IRS indicates AMT may apply
Form 6251 is typically filed with your annual tax return, not separately.
IRS Notices This Form Is Commonly Used With
Form 6251 is often associated with IRS notices that reflect tax recalculations or adjustments, including:
- CP14 – When AMT creates an unexpected balance due
- CP2000 – When income adjustments trigger AMT recalculation
- Audit or adjustment letters involving tax preference items
Form 6251 determines tax liability; it does not respond to collection or enforcement notices.
When NOT to Use Form 6251
Do not use Form 6251 if:
- Your income and deductions do not trigger AMT
- You are correcting a simple reporting error (use Form 1040-X)
- You are responding to penalties, interest, or fees (Form 843 applies)
- You are dealing with collection actions such as levies or liens
Form 6251 is strictly a tax calculation form.
What Information Is Required on Form 6251?
Form 6251 generally requires:
- Income and deduction amounts from your tax return
- Adjustments for AMT preference items
- Calculations of AMT exemption and phaseouts
- Final comparison between regular tax and AMT
Most taxpayers complete Form 6251 using tax software due to calculation complexity.
Where and How to File Form 6251
Form 6251 is filed:
- As part of your Form 1040 or 1040-SR
- Electronically or by mail with your annual return
- Alongside other required schedules
It is not filed independently.
What Happens After You File Form 6251?
After filing:
- The IRS processes the AMT calculation with your return
- If AMT applies, it is added to your total tax liability
- Errors or omissions may result in adjustment notices
- Future tax years may also require AMT review
Related IRS Forms
Other forms commonly associated with AMT include:
- Form 1040 / 1040-SR – Individual income tax return
- Form 1040-X – Amended return if corrections are needed
- Form 8801 – Credit for Prior Year Minimum Tax
Summary
IRS Form 6251 is used to determine whether the Alternative Minimum Tax applies and to calculate any additional tax owed. It is a calculation-focused form that ensures certain deductions and income items are properly accounted for under AMT rules.
Scope Note
This page explains the purpose and general use of IRS Form 6251. It does not provide legal or tax advice.