512-S: 2025 Form 512-S Oklahoma Small Business Corporation Income Tax Return Packet & Instructions (2025)

Who files this form

File Oklahoma Form 512-S if your corporation:

• Has an election in effect under Subchapter S of the Internal Revenue Code;
• Does business in Oklahoma or receives income from property located in Oklahoma; and
• Is required to file federal Form 1120-S.

Use Form 512-S, not Form 512. An Oklahoma return is still required when federal and Oklahoma net distributable income are the same.

When it's due

For the 2025 return, the filing deadlines printed in the packet are:

• Regular return: No later than 30 days after the federal return's due date.
• Complete liquidation or dissolution: On or before the 15th day of the fourth month following the month in which the corporation is completely liquidated.
• Office closures: If the last filing day falls on a day when Oklahoma Tax Commission offices are closed, filing by the end of the next business day is timely.

A valid federal filing extension automatically extends the Oklahoma filing deadline if no Oklahoma tax liability is owed. Provide a copy of the federal extension with the Oklahoma return. If the federal return is not extended, or Oklahoma tax is owed, an Oklahoma filing extension may be granted on Form 504-C. Pass-through entities use Form 504-PTE.

What you'll need

Have these records and documents ready:

• A complete copy of federal Form 1120-S and all required schedules, including Schedule K-1.
• Balance sheets from your financial statements if you are not required to complete federal Schedules L and M-1.
• Your federal employer identification number (FEIN), plus each shareholder's name, address, SSN or FEIN, and share of net income.
• Form 512-S-SUP if there are more than two shareholders. Use as many copies as needed to list everyone.

Depending on your return, also provide:

• Signed Forms 512-SA for nonresident shareholders, except shareholders of an electing pass-through entity, if the corporation is not paying tax on their shares of income.
• Form 587-PTE if the corporation is an electing pass-through entity, and Form 586 for a first-year election made with the return.
• Withholding statements, such as Forms 500-A, 500-B, 1099-MISC, or federal Schedule K-1, to support withholding claimed or passed through.
• Required forms and schedules supporting deductions, exclusions, and credits.
• A copy of the federal extension if relying on it to extend the Oklahoma filing deadline.

How to file

Electronic filing is required for Form 512-S under Rule 710:50-17-1. Visit tax.ok.gov for approved electronic filing products.

To prepare the return:

1. Start with Part 2. All S corporations complete Column A of Parts 2 and 3.
2. Complete the applicable Oklahoma income calculations. The packet directs businesses using direct accounting to Column B of Parts 2 and 3, and businesses of a unitary nature to Part 4.
3. Complete Part 5 for all shareholders, using Form 512-S-SUP when there are more than two shareholders.
4. Complete Part 1 when reporting tax for nonresident shareholders without Form 512-SA, filing as an electing pass-through entity, or claiming the refundable credit for electricity generated by zero-emission facilities.
5. Provide the federal return and required supporting documents. Sign the return and keep copies for your records.

Common mistakes

• Using Form 512 instead of Form 512-S. The packet specifically says not to use Form 512.
• Omitting federal documents. Missing the complete federal return or required balance sheets can delay processing of the corporation's and shareholders' returns.
• Leaving out tax-year information. For fiscal-year and short-period returns, enter beginning and ending dates. Mark the applicable fiscal-year, short-year, or 52/53-week-year checkbox. Missing information may significantly delay processing, and no interest will accrue on a pending refund.
• Incorrect FEINs, calculation errors, or missing signatures. The packet reminds filers to check identification numbers and calculations and sign their returns.
• Missing direct deposit information. Refunds must be made by direct deposit. Missing information delays refund processing.
• Netting depreciation adjustments. Report the federal depreciation add-back and Oklahoma bonus depreciation subtraction in full, rather than combining them into one net amount.
• Omitting Form 569 for transferred, allocated, or assigned credits. The packet warns that the affected credits will be denied.

Questions people ask

What happens if a nonresident shareholder does not provide Form 512-SA?

Except for shareholders of an electing pass-through entity, a signed Form 512-SA must accompany the original return to avoid corporation-level tax on that shareholder's share of net income. If the agreement is missing from the original return, the corporation's tax is binding. A signed agreement is irrevocable for that tax year and must include the shareholder's SSN or FEIN.

Can the corporation elect to pay tax as a pass-through entity?

Yes. A pass-through entity required to file an Oklahoma S corporation return may make the election using Form 586. For a first-year election with the return, mark the first-year PTE election box and provide Form 586. Electing entities also mark the electing PTE box and use Form 587-PTE to compute the tax. The election remains binding until revoked by the entity or the Oklahoma Tax Commission.

How will a refund be paid?

Refunds must be made by direct deposit. Failure to provide direct deposit information will delay processing.

How do I amend a return?

Use Form 512-S, mark the amended-return box at the top of page 1, and complete Schedule 512-S-X on page 9. Provide federal amended Form 1120-S when applicable. An overpayment on an amended return is refunded and cannot be credited to estimated tax. The amount applied to estimated tax on the original return cannot be adjusted.

Official sources

• https://oklahoma.gov/content/dam/ok/en/tax/documents/forms/businesses/corporate-income-tax/current/512-S-Pkt.pdf