512: 2025 Form 512 Oklahoma Corporation Income Tax Return Packet & Instructions (2025)
Oklahoma · Oklahoma Tax Commission · Used for tax years 2025
Form 512 is Oklahoma’s corporation income tax return. The 2025 packet provides instructions for determining Oklahoma taxable income and tax, along with forms for computing consolidated taxable income.
Who files this form
Any corporation doing business in Oklahoma or receiving income from Oklahoma sources must file an Oklahoma Corporation Income Tax Return, even if no tax is due.
Small Business Corporations (Subchapter S) must use Form 512-S instead of Form 512.
When it's due
For tax year 2025:
- Return deadline: Your Oklahoma return is due no later than 30 days after the federal return due date.
- Complete liquidation or dissolution: The return is due on or before the 15th day of the fourth month following the month in which the corporation is completely liquidated.
- Estimated payments: Installments are due on or before the 15th day of the fourth, sixth, and ninth months of the taxable year, and the first month of the succeeding taxable year.
- Extension request: File Form 504-C on or before the return's due date if your federal return is not extended or you owe Oklahoma tax. If no Oklahoma liability is owed, an approved federal filing extension automatically extends the Oklahoma filing deadline. Include a copy of the federal extension with your return.
If a deadline falls on a day when OTC offices are closed, filing or performing the required act by the end of the next business day is considered timely.
The packet says to pay 90% of the income tax liability with the extension to avoid a late-payment penalty, and 100% to avoid late-payment interest.
What you'll need
Have these items ready:
- Your completed federal income tax return, including a complete copy and all required schedules.
- Your Federal Employer Identification Number (FEIN).
- Your tax year's beginning and ending dates if filing a fiscal-year or short-period return.
- Bank routing and account information for a direct-deposit refund.
- Completed Form 512 pages 7 and 8, or copies of federal Form 1120 Schedules L, M-1, and M-2. If you are not required to complete those federal schedules, you must still complete the Oklahoma balance sheet and reconciliation schedules. If federal Schedule M-3 replaces Schedule M-1, complete Oklahoma Schedule M-1 or provide federal Schedule M-3.
Depending on your return, you may also need:
- A copy of your approved federal filing extension.
- A detailed schedule for any net operating loss carried forward.
- Form 511-CR and applicable supporting forms or schedules for credits claimed on that form.
- Form 500-A, Form 1099-MISC, Form 500-B, Form K-1, or other proof of Oklahoma withholding.
- Form 561-C, federal Schedule D, and Form 8949 or 4797, when applicable, for an Oklahoma capital gain deduction.
For a consolidated Oklahoma return, complete Form 512-TI and separate Form 512 pages 3–8 for each company. Provide the federal consolidated return and each member's income statement, balance sheet, Schedules M-1, M-2, M-3, and supporting schedules.
How to file
- Complete your federal return first. Use that information to prepare your Oklahoma return. All corporations start with Part 1, Column A.
- Round amounts to whole dollars. When adding amounts for a line, include cents in the calculation and round only the final total.
- File electronically. Oklahoma Corporation Income Tax Returns must be e-filed. Visit tax.ok.gov for approved electronic filing products.
- Keep copies of all completed documents for your records.
Paying your tax
Pay online through OkTAP at oktap.tax.ok.gov, or mail a check or money order payable to the Oklahoma Tax Commission. Include Form EF-V or an estimated tax coupon, Form OW-8-ESC, with a mailed payment.
Send mailed payments to:
Oklahoma Tax Commission
PO Box 26890
Oklahoma City, OK 73126-0890
Do not include a copy of your return with a mailed payment. Make estimated income tax payments separately.
Common mistakes
- Missing or incorrect FEIN: Check your FEIN on every form and schedule.
- Missing tax-year information: Enter fiscal-year or short-period dates and check the appropriate tax-year box if you are not a calendar-year taxpayer. Missing information can significantly delay processing, and no interest accrues on a pending refund.
- Incomplete federal attachments: Include a complete federal return and all required schedules to avoid processing delays.
- Calculation or signature errors: Check calculations carefully, round as instructed, and do not forget to sign the return.
- Missing direct-deposit information: This delays refund processing. Refunds generally must be made by direct deposit, with limited exceptions.
- Netting bonus depreciation adjustments: Report the full federal depreciation add-back and the full Oklahoma bonus depreciation subtraction separately. Do not net them.
- Omitting Form 569: Transferred or allocated tax credits must be reported on Form 569. Otherwise, the affected credits will be denied.
Questions people ask
What is the corporation income tax rate for 2025?
The packet states that the income tax rate is 4%.
Do corporations have to make estimated tax payments?
Yes, when the current year's tax liability can reasonably be expected to be $500 or more. Estimated payments are the lesser of 70% of the current year's tax liability or 100% of the tax liability shown on the preceding 12-month tax year's return.
How will the corporation receive its refund?
Refunds generally must be made by direct deposit, with limited exceptions. Complete the direct-deposit section and select checking or savings. If a financial institution refuses the deposit, a check will be issued to the address on the return. OTC does not allow direct deposits to or through foreign financial institutions; taxpayers using them receive a paper check.
Can Form 512 be used to amend a return?
Yes. Form 512 is used for amended returns. The packet states that line 13 cannot be amended or changed once the original return has been processed.