MO-A: Individual Income Tax Adjustments (2025)
Missouri · Missouri DOR · Used for tax years 2025
Form MO-A is Missouri’s 2025 Individual Income Tax Adjustments form, attached to Form MO-1040. It reports additions and subtractions to federal adjusted gross income and calculates Missouri itemized deductions and deductions for pensions, Social Security, and Social Security disa
Who files this form
Form MO-A is an attachment to Form MO-1040 for reporting Missouri income adjustments and calculating certain deductions. It covers:
- Additions to and subtractions from federal adjusted gross income.
- Missouri itemized deductions. Complete Part 2 only if you itemize deductions on your federal return.
- Pension, Social Security, and Social Security disability deductions.
What you'll need
- Your federal return: The form says to attach it.
- For Missouri itemized deductions: Attach Federal Form 1040, pages 1 and 2, and Federal Schedule A.
- For exempt federal obligation interest: Attach a detailed list or all Federal Forms 1099.
- For qualified health insurance premiums: Attach the Qualified Health Insurance Premiums Worksheet, Form 5695, and supporting documentation.
- For pension and Social Security calculations: Have the applicable amounts from Federal Form 1040 or 1040-SR, lines 4b, 5b, and 6b, and Form MO-1040, line 6.
How to file
Attach Form MO-A to Form MO-1040, along with your federal return and the supporting documents required for the entries you complete.
Transfer these totals to Form MO-1040:
- Part 1, line 7, total additions, to line 2.
- Part 1, line 19, total subtractions, to line 4.
- Part 2, line 12, Missouri itemized deductions, to line 14.
- Part 3, Section D, total pension and Social Security/Social Security disability deduction, to line 8.
The supplied form does not give a mailing address or e-filing directions.
Common mistakes
- Completing Part 2 without federal itemized deductions: The form says to complete this part only if you itemize on your federal return.
- Leaving out required attachments: Include your federal return and any supporting documents required for the deductions or adjustments you report.
- Missing the Social Security age requirement or checkbox: For the 2025 Social Security deduction, you must be age 62 by December 31 and select the “62 and older” box on page 1 of Form MO-1040. The age limit does not apply to the Social Security disability deduction.
- Skipping the Social Security calculation when calculating a public pension deduction: If you received taxable Social Security, Section A tells you to complete Section C, lines 1 through 3, and enter the applicable amounts in Section A.
Questions people ask
Can I complete the Missouri itemized deductions section if I do not itemize federally?
No. Part 2 says to complete it only if you itemize deductions on your federal return.
When do I use the Part 2 net state income taxes worksheet?
Complete it only if your total state and local taxes included in federal itemized deductions exceeded $40,000, or $20,000 if married filing separately, or if you were required to complete a federal worksheet to calculate Federal Schedule A, line 5e.
What counts as a public or private pension on this form?
Public pensions are pensions received from a federal, state, or local government. The private pension calculation covers annuities, pensions, IRAs, and 401(k) plans funded by a private source.
Does the Social Security disability deduction have an age limit?
No. The form states that the age limit for the Social Security deduction does not apply to the Social Security disability deduction.