U.S. · W-2 box 12
W-2 box 12 code S.
Your SIMPLE IRA deferrals, with the lower SIMPLE limits.
Code S is the amount you deferred into a SIMPLE IRA from your pay. A SIMPLE has its own, lower limit: $17,000 for 2026 ($18,100 in certain plans), plus catch-up. If the SIMPLE is part of a 401(k) arrangement, the IRS says to use code D instead.
Check your code S amount
Result
What code S means
IRS description: Code S: Employee salary reduction contributions under a section 408(p) SIMPLE plan (this includes salary reduction contributions made to a Roth SIMPLE IRA).
A SIMPLE IRA is the small-employer plan many businesses with a few staff offer. Code S shows what you elected to take out of your pay for it. The IRS adds an important routing rule: "if the SIMPLE plan is part of a section 401(k) arrangement, use code D." So a W-2 with D instead of S does not mean your employer picked the wrong letter; it may be a SIMPLE 401(k).
There is also a Roth variation. The IRS definition includes salary reduction contributions made to a Roth SIMPLE IRA. The difference shows up in box 1: the IRS lists Roth IRA salary reduction under a SEP or SIMPLE arrangement among the amounts included in box 1, while a pre-tax SIMPLE deferral is not.
Where code S shows up on your W-2 and return
- Box 1: a pre-tax SIMPLE deferral is not included. Salary reduction contributions made to a Roth SIMPLE IRA are included.
- Boxes 3 and 5: included. The IRS lists code S with the deferral codes reported in box 3.
- Box 13: the "Retirement plan" box applies, because the IRS list of active-participant plans includes a SIMPLE retirement account under section 408(p).
- Form 1040: no entry for a deferral inside the limit. If you went over, the plan has to return the excess.
Worked example
Marcus earns $48,000 at a five-person shop and defers $3,000. Box 12 shows S 3000.00. Box 1 is $48,000 − $3,000 = $45,000, and boxes 3 and 5 are $48,000. He is well under the SIMPLE limit of $17,000. If his employer's plan were a SIMPLE 401(k) the same $3,000 would show as D 3000.00 instead.
Limits and what to check
The IRS announced the 2026 SIMPLE limit at $17,000, with a higher $18,100 for certain applicable plans. Catch-up for age 50 and over is generally $4,000 ($3,850 in certain applicable plans), and $5,250 for ages 60 to 63 (IRS news release, read November 1, 2026). These are lower than the 401(k) numbers, and different plan types can carry different limits. If you changed jobs or had more than one plan, list every deferral code on your W-2s (S, D, E, G) and ask the plan administrators which limit applies to the combination.
Common mistakes
- Using the $24,500 401(k) limit for a SIMPLE IRA. The SIMPLE limit is $17,000 ($18,100 in some plans).
- Assuming a D on the W-2 means a regular 401(k). A SIMPLE that is part of a 401(k) arrangement is reported with D.
- Expecting a Roth SIMPLE to reduce box 1. Roth salary reduction stays in box 1.
- Counting the employer match or nonelective contribution. Only your salary reduction is code S.
See every code in one searchable table on the W-2 box 12 codes lookup.
Sources
Primary sources opened on November 1, 2026. The plain-English parts of this page are our summary of them, not IRS guidance.
- IRS, General Instructions for Forms W-2 and W-3 (2026), Box 12, Codes (read 2026-11-01): code S definition, the SIMPLE 401(k) routing rule, box 1 and box 3 lists
- IRS news release: 401(k) limit increases to $24,500 for 2026 (read 2026-11-01): 2026 SIMPLE limits and catch-up amounts
Frequently asked questions
What does code S mean on a W-2?
Code S reports your salary reduction contributions to a SIMPLE plan under section 408(p), including salary reduction to a Roth SIMPLE IRA.
Why does my SIMPLE show as code D?
The IRS says that when a SIMPLE plan is part of a section 401(k) arrangement, the employer must use code D rather than S.
What is the 2026 SIMPLE IRA limit?
$17,000, or $18,100 for certain applicable SIMPLE plans. Catch-up is $4,000 ($3,850 in certain plans) at 50 and over and $5,250 at ages 60 to 63.
Is code S in box 1?
A pre-tax SIMPLE deferral is not in box 1, but it is in boxes 3 and 5. Salary reduction to a Roth SIMPLE IRA is included in box 1.
Does code S include the employer contribution?
No. Code S is only your own salary reduction. Employer contributions are not reported in box 12.
Do I report code S on Form 1040?
Not for a deferral within the limit. If your deferrals were over the limit, the plan returns the excess and the Form 1040 instructions explain how it is reported.
Not tax advice
This page summarizes IRS instructions written for employers and is not tax advice. Your payroll provider, plan administrator or a tax professional can confirm what a code means on your own form. Everything runs in your browser; nothing you enter is sent anywhere.