Maryland Form 502SU is the schedule you attach to your Form 502 to claim subtractions from income that aren’t already handled on a numbered line of the main return. Each eligible subtraction has a code letter, you list the amount next to each code that applies, and the total flows to Line 13 of Form 502 to reduce your Maryland taxable income. Skip the form when you were supposed to file it and the Comptroller will disallow the subtraction.
When You Need to File Form 502SU
The form is for Maryland residents and part-year residents filing Form 502.1Comptroller of Maryland. 2025 Individual Income Tax Forms You need it any time you qualify for a Maryland subtraction beyond what the main return already covers on its own lines (the Social Security exemption and the standard pension exclusion are built in, for example).
There is one shortcut. If only a single subtraction applies to you, you can put the amount and its code letter directly on Line 13 of Form 502 without attaching the separate schedule.2Comptroller of Maryland. 2025 State and Local Tax Forms and Instructions Two or more subtractions and you have to file the form.
If you live in another state and earned income in Maryland, Form 502SU isn’t the right form. Nonresidents file Form 505 and use the parallel Form 505SU, which carries the same code letters but is not interchangeable.3Comptroller of Maryland. 2025 Maryland Nonresident Tax Forms and Instructions
The Subtractions Filers Claim Most Often
The 502SU code list runs through the alphabet, but a handful of items cover most returns. The amounts and conditions below apply to tax year 2025, filed in 2026.
Military Retirement Income (Code u)
Up to $20,000 of military retirement income if you were 55 or older on the last day of the tax year, or up to $12,500 if you were under 55.4Comptroller of Maryland. Maryland Form 502SU Subtractions From Income Only the portion that was included as taxable income on your federal return is subtractable. Your Form 1099-R shows the distribution.
Overseas Military Pay (Code p)
Active-duty pay earned while stationed outside the United States or its possessions can be subtracted up to $15,000. The Form 502 instructions include a worksheet for the eligible amount.2Comptroller of Maryland. 2025 State and Local Tax Forms and Instructions
Maryland 529 Plan Contributions
Contributions to a Maryland College Investment Plan or Prepaid College Trust are subtractable up to $2,500 per beneficiary per year, with excess amounts carried forward and subtracted over the next 10 years.5Maryland 529. Tax Advantages Only Maryland 529 plans qualify. Keep your contribution receipts; the Comptroller can ask for them.
Adoption Expenses (Code k)
Up to $12,000 in expenses for adopting a child with special needs through a public or nonprofit agency, or up to $10,000 for adoptions of children without special needs.4Comptroller of Maryland. Maryland Form 502SU Subtractions From Income
Pass-Through Entity Adjustments (Code b)
If you receive a Maryland Schedule K-1 from a partnership, S corporation, or other pass-through entity, any net subtraction modifications reported to you on that K-1 go here. The amount comes from the entity, not from a calculation you do yourself.2Comptroller of Maryland. 2025 State and Local Tax Forms and Instructions
Other Subtractions Worth Knowing
- Fire, rescue, and ambulance length-of-service award payments from a county or municipal program (code n).
- Up to $5,000 in reader expenses for a blind person, or up to $1,000 for an employer providing a reader (code h).
- Pickup contributions to a Maryland state retirement system, as shown on your 1099-R, that were included in your federal income (code r).
- Firefighter and police disability pension payments for job-related injuries, up to the amount included in your federal income (code a).
Each code has its own eligibility rules and documentation. The Form 502 instruction booklet spells them out code by code, and that’s the first place to check before claiming any subtraction you aren’t familiar with.2Comptroller of Maryland. 2025 State and Local Tax Forms and Instructions
How to Fill Out Form 502SU
The form itself is short. Put your name, Social Security number, and the tax year at the top. Each subtraction has its own line identified by a code letter. Enter the dollar amount next to each code that applies, add them up, and transfer the total to Line 13 of Form 502. Also enter the code letters for your four largest subtractions in the boxes provided on Form 502.4Comptroller of Maryland. Maryland Form 502SU Subtractions From Income
Pull your documentation before you start. What you need depends on which subtractions you’re claiming:
- Military retirement: your Form 1099-R.
- 529 contributions: receipts or account statements from Maryland 529.
- Pass-through adjustments: the Maryland Schedule K-1 from the entity.
- Adoption expenses: receipts from the public or nonprofit agency.
- Artist’s contributions (code m): Form 502AC, which must be attached.
The Rule That Catches People
You can only subtract income that was included as taxable income on your federal return. If a payment wasn’t taxable federally, there is nothing on the Maryland side to subtract. Claiming a subtraction for income that was never in your federal AGI creates a double benefit, and the Comptroller will correct it.
How to Submit It
If you e-file through tax software, the 502SU data feeds into your Form 502 automatically and no extra step is needed. On paper, place the completed Form 502SU directly behind Form 502. Include copies of all W-2s and 1099s showing Maryland withholding. If you are also claiming a credit for taxes paid to another state, include a copy of that state’s return in the package.
Paper returns go to the Comptroller of Maryland. If you owe a balance, send a check or money order payable to the Comptroller with the return, or pay through the Comptroller’s online payment portal for an immediate confirmation.
Deadline and Extensions
For tax year 2025, your Maryland return and Form 502SU are due April 15, 2026.6Comptroller of Maryland. What’s New for the 2026 Tax Filing Season
Maryland offers a six-month extension, and how you get it depends on whether you owe. If you’ve already requested a federal extension and don’t owe additional Maryland tax, the Maryland extension is automatic with no extra filing. If you haven’t requested a federal extension but still don’t owe state tax, you can request the six-month extension online or by calling the Comptroller.7Comptroller of Maryland. Tax Guidance – Extensions
If you do owe tax, file Form PV with a payment for the expected balance by April 15. Form PV extends the time to file but not the time to pay. Interest accrues on any unpaid balance from the original due date regardless of the extension.7Comptroller of Maryland. Tax Guidance – Extensions
What Happens If You Get It Wrong
Understating your Maryland tax because of an incorrect subtraction means owing the additional tax plus interest. Late payment penalties can reach up to 25% of the tax owed.8Comptroller of Maryland. Penalty and Interest Charges
If an incorrect subtraction flows through to your federal return, the IRS can impose a 20% accuracy-related penalty for substantial underpayment, which for individuals means understating tax by the greater of 10% of the correct tax or $5,000.9Internal Revenue Service. Accuracy-Related Penalty
The far more common outcome is simpler: you claim a subtraction on Form 502, forget to attach Form 502SU, the Comptroller disallows it, and a bill shows up for the difference. Attach the form, keep the documentation, and that doesn’t happen.