To file an Alabama amended tax return, complete a new Form 40 with the corrected figures, check the “Amended” box at the top of page one, attach a written explanation of what changed, and mail the package to the Alabama Department of Revenue. Alabama does not accept amended returns electronically, so the process is entirely on paper, and manual review means it takes longer than an original filing.
When You Should Amend
The most common trigger is a federal change. If the IRS adjusts your federal return, or you file a federal Form 1040-X yourself, and the change moves your Alabama taxable income, you need to file a matching state amendment.1Internal Revenue Service. File an Amended Return
Other situations that call for an amended return:
- You misreported income (a forgotten W-2, missing freelance earnings, a wrong 1099 amount).
- You missed a deduction or credit you were entitled to, such as an education credit, charitable contribution, or itemized deduction.
- You used the wrong filing status.
You do not need to amend if the ADOR or IRS already corrected a math error on your original return and sent you a notice about it. That correction is the fix.
Deadline to File
If the amendment claims a refund, you generally have three years from the date you filed the original return, or two years from the date you paid the tax, whichever is later. If you never filed a timely return in the first place, that window shrinks to two years from the date of payment.2Alabama Department of Revenue. What Is the Time Limit for Requesting a Refund
If the amendment shows you owe more tax, no deadline works in your favor. File as soon as you find the error, because penalties and interest keep running from the original due date.
How to Fill Out the Amended Return
The ADOR instructs you to complete a new individual income tax return, the same Form 40 you originally filed, using the corrected numbers, then check the “Amended” box at the top of page one.3Alabama Department of Revenue. How Do I File an Amended Return Before you start, gather:
- Your original Alabama return
- Any IRS notices or your federal Form 1040-X, if federal changes are the reason
- Supporting documents for what changed: corrected W-2s, updated 1099s, receipts for newly claimed deductions
Fill in every line as it should have been the first time. The department compares the amended version against your original on their end.
Attach a written explanation of the changes, and be specific. Reference line numbers and describe each adjustment plainly: “Line 12 increased by $3,200 to reflect a corrected W-2 from [employer name]” is the level of detail that keeps things moving. Vague phrasing like “correcting errors” invites follow-up letters.
Where to Mail It
Print and sign the return, then mail it with your explanation and copies of all supporting documents to:
Alabama Department of Revenue
Individual & Corporate Tax
P.O. Box 327464
Montgomery, AL 36132-74644Alabama Department of Revenue. Forms Mailing Addresses
Keep a full copy of what you send. The ADOR does not acknowledge receipt, so a certified mail tracking number is your only proof of the submission date.
Paying a Balance Due
If the amended return shows additional tax, pay when you file rather than waiting for a bill. Penalties and interest accrue from the original due date of the return, not from the date you discovered the mistake.
You can pay online through the My Alabama Taxes portal by bank draft (ACH) or credit or debit card, or mail a check or money order with the return.5Alabama Department of Revenue. Income Tax Payment Options Make checks payable to the Alabama Department of Revenue, and write your Social Security number and the tax year on the memo line.
Penalties and Interest If You Owe
Alabama charges both a penalty and interest on unpaid tax, and they run at the same time.
The failure-to-pay penalty is 1% of the unpaid tax for each month or partial month the balance is outstanding, up to a maximum of 25%.6Alabama Legislature. Alabama Code Title 40 Revenue and Taxation 40-2A-11 File six months after the original due date and the penalty alone is 6% of the additional tax.7Alabama Administrative Code. Alabama Administrative Code 810-14-1-.30 – Penalty for Failure to Timely Pay Tax
Interest is calculated separately, on top of the penalty. Alabama sets the underpayment rate quarterly under Section 40-1-44 of the Alabama Code. For the first quarter of 2026, the rate is 7% per year.8Alabama Department of Revenue. Quarterly Interest Rates The rate changes from quarter to quarter, so an underpayment that spans several quarters may carry different rates for different periods. Paying when you file the amendment is the cheapest option by a wide margin.
Checking on a Refund
If your amendment produces a refund, expect the wait to be much longer than an original return. The ADOR advises allowing at least six weeks after filing, and amended returns often take longer because they require manual review.
You can check refund status through the My Alabama Taxes portal at myalabamataxes.alabama.gov.9Alabama Department of Revenue. How Can I Check on My Individual Income Tax Refund If the tool shows no update, the most likely reason is that your return has not yet reached the reviewer’s queue.