Guide  ·  Form 1120-S

Box 13, code M.

An S corporation computes the federal R&D tax credit (Section 41) on Form 6765 and passes it to shareholders on Schedule K-1, box 13, code M. The entity never files Form 3800 for it. This guide covers only what is specific to Form 1120-S.

Schedule K, line 13gOther credits, code M. Checked against the 2025 instructions.
K-1, box 13, code Mcarries each shareholder's share to their own Form 3800.
Item Athe Section 280C election, is answered on the entity Form 6765.

The route

Form 1120-S (2025)
StepForm and lineRevision checked
Compute the creditForm 6765, line 30, with Item A answered at the entity levelForm 6765 (Rev. December 2024)
Report on the entity returnSchedule K, line 13g, Other credits, code MInstructions for Form 1120-S (2025)
Pass to each shareholderSchedule K-1, box 13, code M, Credit for increasing research activitiesInstructions for Form 1120-S (2025)
Shareholder claims itForm 3800, Part III, line 1c, entity EIN in column (c), then the shareholder returnForm 3800 (2025)
Deduct the research costSection 174A deduction with other deductions on line 20; amortized amounts on Form 4562, Part VIInstructions for Form 4562 (2025)
Amend a prior yearForm 1120-S with the amended return box checkedInstructions for Form 1120-S (2025)

Steps for the preparer

  1. Attach Form 6765 completed through line 30 and stop there. The S corporation does not file Form 3800 for this credit. Item A, the Section 280C election, is answered on this entity form. The Form 6765 guide covers each section.
  2. Enter line 30 on Schedule K, line 13g with code M. A qualified small business making the payroll election reports line 30 reduced by line 36, and claims line 36 on its own Form 941 through Form 8974.
  3. Allocate to shareholders pro rata on Schedule K-1, box 13, code M, with a statement if any shareholder needs more than the amount.
  4. The shareholder enters the box 13 code M amount on Form 3800, Part III, line 1c, with the S corporation EIN in column (c), in column (d) or (e) depending on material participation. The Form 3800 guide and the Form 1040 guide take it from there.
  5. Report the expense. For tax years beginning after December 31, 2024, domestic research or experimental expenditures are deducted in the year paid or incurred under Section 174A, or capitalized and amortized over not less than 60 months by election. Foreign research stays under Section 174 and is amortized over 15 years. Amortized amounts are reported on Form 4562, Part VI, with 174A in column (d). Revenue Procedure 2025-28 sets out the transition choices for costs capitalized in 2022 through 2024.

Amended returns

Common questions

Who makes the Section 280C election, the S corporation or the shareholder?

The S corporation, on Item A of the Form 6765 it attaches. The shareholder receives a credit already computed at the elected rate.

Can the S corporation use the credit against its own tax?

No. The credit passes through to the shareholders. The one exception is the payroll tax election, which the entity claims on Form 941.

Does the shareholder need a copy of Form 6765?

Not to file. The K-1 amount is enough for Form 3800. Keep the entity copy in the file for examination.

Sources

Related guides

  • Form 6765Completing Form 6765, the credit form itself.
  • Form 3800Where the research credit goes on Form 3800 and how it reaches the return.
  • Form 1120C corporations: Schedule J, Section 174A, and Form 1120-X.
  • Form 1065Partnerships: Schedule K line 15f, K-1 box 15 code M, and the partner.
  • Form 1040Individuals: Schedule 3 line 6a, Schedule C, and Form 1040-X.
  • Form 1041Estates and trusts: Schedule G line 2b and K-1 box 13 code I.

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