Oklahoma Tax Deadlines After Death: The Executor's Filing Calendar

As an executor in Oklahoma, you are responsible for filing returns and meeting deadlines on behalf of the person who died — some within months of the death. Missing these deadlines can mean penalties, interest, and liens that complicate estate distribution. Here is a complete filing calendar with every deadline you need to track.

The First Priority: Death Certificates

Before you can do almost anything — open an estate account, notify agencies, file tax returns — you need certified copies of the death certificate.

Where to get them: The Oklahoma State Department of Health (OSDH) issues certified copies through VitalChek or by mail.

Cost: $15 per certified copy from OSDH. For non-resident online orders, there is an additional $12.95 processing fee.

How many to order: Get at least 10 certified copies. Banks, insurers, transfer agents, and government agencies each require an original certified copy — they do not accept photocopies. Running short means ordering more and waiting, which delays everything else.

Timing: Order immediately after death. Processing typically takes 7–10 business days for online orders. Expedited options exist through VitalChek for an additional fee.

Oklahoma Income Tax: Form 511 (Deceased Individual)

The deceased's final Oklahoma income tax return covers January 1 of the year they died through the date of death.

Form to file: Oklahoma Form 511 (resident individual income tax return). Write "DECEASED" across the top along with the date of death.

Who files it: The executor or personal representative. If there is a surviving spouse and they are filing a joint return (permitted on the final return), the surviving spouse signs.

Deadline: April 15 of the year following death — the standard income tax filing deadline.

Extension: Oklahoma follows federal extension rules. If you file for a federal extension (Form 4868), Oklahoma automatically grants a corresponding extension to October 15. The extension is for filing only, not for any tax owed — pay any estimated balance by April 15 to avoid interest.

One thing to watch: If the decedent had estimated tax payments, withholding, or overpayments on the return, those refunds belong to the estate. Do not simply cash a check made out to the deceased — it needs to go through the estate account.

Oklahoma Estate (Fiduciary) Income Tax: Form 513

Once the estate itself earns income — dividends, interest, rental income, royalties from oil and gas — it becomes a taxpaying entity. The executor must file a fiduciary income tax return for the estate.

Form to file: Oklahoma Form 513 (Oklahoma Fiduciary Income Tax Return)

Deadline: The 15th day of the 4th month after the close of the estate's tax year. Most estates adopt a calendar year, making the deadline April 15. Some adopt a fiscal year ending on a month other than December, which shifts the deadline accordingly.

When this applies: Form 513 is required for any estate that has gross income of $1,000 or more during the tax year. This includes income generated between the date of death and the closing of the estate.

What to report: Oklahoma follows federal fiduciary income tax rules. The return reports income earned by the estate, deductions, and distributions to beneficiaries. Distributions to beneficiaries are generally deducted on the estate's return and reported as income to the beneficiary on a K-1.

Fiscal year election: The estate can elect a fiscal year ending on any month within the first year of administration. Choosing a non-calendar fiscal year can shift income and simplify tax planning. Make this election by filing the first Form 513 with the chosen year-end.

Federal Estate Tax: Form 706

Oklahoma no longer has a state estate tax — it was tied to the federal pick-up tax and effectively eliminated when the federal estate tax changed in 2001. Pre-2010 deaths may involve estate tax lien questions (see below), but for deaths in 2010 and later, there is no Oklahoma estate tax return to file.

There is, however, a potential federal estate tax obligation.

Form to file: IRS Form 706 (United States Estate and Generation-Skipping Transfer Tax Return)

Deadline: 9 months after the date of death. Extensions are available for an additional 6 months (Form 4768), but any tax owed must be paid within the original 9-month deadline to avoid interest and penalties.

2026 threshold: The federal estate tax exemption for 2026 is approximately $13.99 million per person ($27.98 million for married couples with portability election). Estates below these amounts owe no federal estate tax.

Portability election: Even if no tax is owed, it may be worth filing Form 706 within 9 months to elect portability — carrying the unused exemption of the deceased spouse to the surviving spouse. This can be valuable for high-net-worth surviving spouses. Missing the 9-month deadline forfeits portability unless a late election is filed within 5 years under Rev. Proc. 2022-32.

Transfer-on-Death Deeds: 9-Month Deadline

Oklahoma recognizes Transfer-on-Death (TOD) deeds as a non-probate transfer mechanism. The beneficiary named on the deed takes the property automatically at death without probate.

Important deadline: The TOD beneficiary must file an affidavit of survivorship with the county clerk within 9 months of the grantor's death to confirm the transfer. Failure to file does not invalidate the transfer, but it can create title complications and delay recognition of ownership by buyers and lenders.

The affidavit must identify the decedent, the date of death, and confirm that the beneficiary survived the grantor.

Claiming a Refund on Behalf of the Deceased: Form 507

If the deceased had an overpayment on their final Oklahoma return — or is owed a refund from a prior year's return — the estate can claim it using Oklahoma Form 507 (Claim for Refund Due a Deceased Taxpayer).

When you need it: If the refund check will be issued to the deceased individually (not to a joint return) and you are not the surviving spouse, Form 507 documents your authority to receive it on behalf of the estate.

What it requires:

• Executor's name, address, and relationship to the decedent
• A copy of the Letters Testamentary or Letters of Administration from the probate court (or, for small estates, an affidavit of heirship or small estate affidavit)
• Proof that no probate proceeding was opened, if claiming without court appointment

Where to file: Attach Form 507 to Form 511 when filing the final income tax return. For prior-year refunds, file Form 507 as a standalone claim with a copy of the prior return.

Common situation: The decedent filed a 2025 return claiming a refund, then died in early 2026 before the refund was received. The estate uses Form 507 to reroute that refund to the estate account.

Oklahoma Estate Tax Lien: Pre-2010 Deaths

Oklahoma had a state estate tax until 2010. For anyone who died before 2010, a potential estate tax lien may still technically exist on real property.

Under 68 O.S. § 804.1, any Oklahoma estate tax lien automatically extinguishes 10 years after the date of death for pre-2010 deaths. This means:

• Deaths before 2000: liens extinguished, no action required
• Deaths between 2000–2010: liens may still be within the 10-year window; verify status with the Oklahoma Tax Commission

For deaths in 2010 or later, there is no Oklahoma estate tax and no estate tax lien.

If you are dealing with a pre-2010 death and a title company or lender is asking about lien release, pull the OTC records and confirm the lien has expired under § 804.1. In many cases, the expiration is automatic and no formal release is needed — but documenting it for title purposes requires the statutory citation.

Summary Filing Calendar

Meeting every tax deadline is just one part of settling an Oklahoma estate. The Oklahoma Estate Settlement Guide has the complete executor checklist including probate court procedures, creditor notice timelines, and asset transfer steps.

See more Oklahoma guides →