Schedule 1-A Walkthrough: How the New Form Fits Into Form 1040

Schedule 1-A, "Additional Deductions," is the form the IRS created to carry the four temporary deductions enacted in 2025. If you use tax software you may never see it directly, but understanding its structure helps you check that your software asked the right questions. This walkthrough follows the form's parts in order and explains what each one needs from your records.

Where the form sits on your return

Form 1040 computes adjusted gross income first. Then, on the deduction lines, you subtract either the standard deduction or itemized deductions, and — new for 2025 through 2028 — the total from Schedule 1-A, which goes on Form 1040 line 13b. Because Schedule 1-A is subtracted after AGI, nothing on it changes AGI. And because it is separate from the standard-or-itemized choice, you get it either way. The IRS describes the deductions as available to itemizers and non-itemizers alike.

Part I: Modified adjusted gross income

The form begins by establishing MAGI, which every phase-out uses. You start with AGI from Form 1040 and add back excluded amounts from Form 2555 (foreign earned income and housing), Form 4563 (American Samoa) and excluded Puerto Rico income. Most filers enter AGI and nothing else. Doing this once at the top is a design choice that keeps the parts consistent: the same MAGI drives the tips, overtime, car loan and senior calculations.

Part II: No tax on tips

This part collects qualified tips. Employees take the qualified amount reported on Form W-2 and tips reported on Form 4137; self-employed people use amounts identified on Forms 1099 or their own records, limited to net profit from the business. The form then applies the $25,000 cap. Next comes the phase-out: subtract $150,000 ($300,000 if married filing jointly) from MAGI, divide the result by 1,000, drop the fraction and multiply by $100. Subtract that from the capped amount, not below zero. The tips calculator does exactly these steps.

The form also asks you to confirm requirements the IRS cannot compute: that the tips were received in an occupation on the official list, that you have a valid Social Security number and that, if married, you are filing jointly.

Part III: No tax on overtime

Part III starts with qualified overtime compensation — the FLSA-required premium — for you and, on a joint return, your spouse. For 2026 wages that amount should come from employer reporting. The form caps it at $12,500, or $25,000 on a joint return, then applies the same $100-per-$1,000 phase-out with round-down. If you had overtime from more than one employer, you add the qualified amounts; each employer's figure reflects its own workweeks.

Part IV: Car loan interest

Part IV asks for the vehicle identification number of each qualifying vehicle and the interest paid during the year. Lenders send statements showing the interest, and the IRS can match the VIN against lender reports. The total is capped at $10,000 per return. The phase-out subtracts $100,000 ($200,000 joint) from MAGI, divides by 1,000, rounds any fraction up, and multiplies by $200. Before you get here, confirm the vehicle and loan tests in our car loan guide; the form assumes you already know the loan qualifies.

Part V: Enhanced deduction for seniors

Part V asks whether you, and your spouse on a joint return, were born before the cutoff date that makes you 65 by year-end, and whether each has a valid SSN. Each qualifying person starts with $6,000. The phase-out is 6% of the excess of MAGI over $75,000 ($150,000 joint), subtracted from each person's amount. Two qualifying spouses each get the same reduction.

The total

The final line adds the four parts; any part that phases out to zero simply contributes nothing. That total flows to Form 1040 line 13b and is subtracted along with your standard or itemized deduction to reach taxable income. If you also claim the qualified business income deduction, it is figured on its own form; Schedule 1-A amounts are separate.

How software handles it

Mainstream tax software builds Schedule 1-A from interview questions: occupation and tip amounts from your W-2, overtime amounts, a VIN and lender interest, and dates of birth. Check three things when you review your return. First, that the tips and overtime figures match your employer's reporting rather than gross overtime pay. Second, that the car loan section shows the correct VIN. Third, that MAGI on the form matches your AGI unless you have foreign or territory exclusions. If you file on paper, the official instructions include worksheets for each part.

A sample completed form, in words

Imagine a single filer with $68,000 AGI: a hotel bell captain with $11,200 of qualified tips on the W-2, $1,800 of qualified overtime premium, and $2,300 of interest on a new US-built pickup. Part I: MAGI $68,000. Part II: $11,200, no reduction. Part III: $1,800, no reduction. Part IV: VIN entered, $2,300, no reduction because MAGI is under $100,000. Part V: not 65, zero. Total: $15,300 to Form 1040 line 13b. With the $16,100 standard deduction, taxable income falls from $51,900 to $36,600. In 2026 that lowers regular tax from about $6,130 to about $4,144 — roughly $1,986 less.

Errors the IRS is likely to catch

Automated matching compares your return with information returns. Expect questions if the tips you claim exceed tips your employer reported, if overtime claimed is far above the employer's qualified figure, if a VIN is missing or does not match a lender report, or if a Social Security number on Part V does not match SSA records for the age claimed. Each of these is preventable by entering numbers straight from the forms.

Amending a return

If you filed a 2025 return without claiming a deduction you were entitled to — for example because your employer did not show overtime separately — you can file Form 1040-X with Schedule 1-A attached. The usual deadline for a refund claim is three years from the original due date. Gather the same documentation you would have used originally.

Why this matters before filing season

Several of the inputs are easy to get wrong or forget: the VIN, the occupation code, the qualified overtime figure. Collecting them in December and January makes the return easier. Our records checklist lists everything by deduction, and the combined calculator lets you test the result in advance.

This walkthrough summarizes the form's structure for education. The official Schedule 1-A and its instructions control.