If someone you love has passed away and you're handling their estate in Connecticut, one of the first deadlines you need to know is when the estate tax return is due. Missing that date can mean penalties, interest charges, and added stress during an already difficult time. Knowing the exact filing deadline and what triggers it helps you stay compliant and avoid costly mistakes with the Connecticut Department of Revenue Services.

When exactly is the Connecticut estate tax return due?

The Connecticut estate tax return is due nine months after the date of death. This applies to the estate tax filing deadline in Connecticut, and it follows the same timeline as the federal estate tax return (IRS Form 706). If the decedent died on March 1, 2024, for example, the Connecticut estate tax return would be due by December 1, 2024.

You file the return using Form CT-706, which is the Connecticut Estate and Gift Tax Return. This form gets filed with the Connecticut Department of Revenue Services (DRS), not the IRS.

What if you need more time to file?

Connecticut allows a six-month extension to file the return, which pushes the deadline to 15 months after the date of death. But here's the catch an extension to file is not an extension to pay. Any estate tax owed is still due by the original nine-month deadline. Interest accrues on unpaid tax from the original due date, even if you've been granted a filing extension.

To request an extension, you generally need to file a request with the DRS before the original due date. The IRS automatic extension for the federal return (Form 4768) does not automatically extend the Connecticut deadline.

Which estates actually need to file a Connecticut estate tax return?

Not every estate owes Connecticut estate tax. Connecticut has its own estate tax exemption threshold, which is $9.1 million for deaths occurring in 2024. This means if the total value of the decedent's taxable estate falls below that amount, no estate tax is due but depending on the circumstances, a return may still need to be filed to claim portability or clarify the estate's value.

Connecticut is one of the few states that imposes an estate tax separate from the federal government. The federal estate tax exemption for 2024 is $13.61 million per individual, which is significantly higher. So an estate could owe Connecticut estate tax while owing nothing federally.

For estates that include retirement accounts, the tax treatment can get complicated. If the estate includes an IRA or other qualified plan, you may also want to review the required forms for estate settlement involving IRA assets.

What happens if you miss the deadline?

Late filing comes with real consequences. The Connecticut DRS charges penalties and interest on any unpaid estate tax. The penalty for late filing can be up to 10% of the tax due, and interest compounds monthly. Even if the estate owes no tax, failing to file when required can create problems later especially if assets need to be transferred, sold, or distributed.

If you've already missed the deadline, filing as soon as possible limits the damage. The DRS may work with executors on payment plans for larger estates.

What documents do you need to file on time?

Staying on schedule means gathering the right paperwork early. You'll need a full accounting of the decedent's assets, including real property, bank accounts, investments, retirement accounts, life insurance, and any gifts made within three years of death. You'll also need the death certificate, the will (if one exists), and prior gift tax returns if applicable.

Reviewing the documents required for Connecticut estate tax filing before the deadline approaches can save you weeks of scrambling. Many executors find it helpful to work with a Connecticut estate attorney or CPA who handles probate and estate tax matters regularly.

How do you actually file the Connecticut estate tax return?

The return is filed on Form CT-706 with the Connecticut DRS. You can file by mail, and Connecticut has been expanding its electronic filing options. The form requires you to list all assets, deductions, and credits. If a federal estate tax return is also required, you'll attach a copy of that as well.

Payment of any estate tax due should accompany the return. The DRS accepts checks and, in some cases, electronic payments.

Common mistakes executors make with the filing deadline

• Confusing the Connecticut deadline with the federal deadline. While both are nine months after death, the extension rules and payment requirements differ.
• Assuming no tax means no filing. Some estates below the threshold still need to file to document asset values or claim deductions.
• Forgetting the three-year lookback on gifts. Connecticut pulls certain gifts back into the taxable estate if they were made within three years of death. This can push an otherwise exempt estate over the threshold.
• Missing the extension payment deadline. Getting extra time to file doesn't mean extra time to pay. Interest starts accruing right away on the original due date.
• Not coordinating with the federal return. Discrepancies between the two returns can trigger audits or delays.

Does the filing deadline change for non-residents with Connecticut property?

Yes, somewhat. If the decedent was not a Connecticut resident but owned real property or tangible personal property located in Connecticut, the estate may still owe Connecticut estate tax on that in-state property. The same nine-month deadline applies, but the calculation is based only on the Connecticut-situs assets rather than the entire estate.

For the most current exemption thresholds and filing requirements, the Connecticut DRS publishes updated guidance on its official website.

Quick checklist for meeting the Connecticut estate tax return deadline

1. Determine the date of death that's your starting point for the nine-month countdown.
2. Find out whether the estate exceeds the Connecticut exemption threshold ($9.1 million for 2024).
3. Gather all asset valuations, including appraisals for real property and business interests.
4. Collect the death certificate, will, prior gift tax returns, and any trust documents.
5. Consult with a Connecticut estate attorney or CPA early ideally within the first month.
6. If you need more time to prepare, file an extension request before the nine-month deadline.
7. Estimate the tax owed and submit payment by the original due date, even if the return isn't ready.
8. File Form CT-706 with the Connecticut DRS by the deadline (or extended deadline if approved).
9. Keep copies of everything you file for at least seven years.

Bottom line: Mark the nine-month deadline from the date of death on your calendar today. If that date feels tight, talk to a tax professional now not next month. Acting early is the single best way to avoid penalties and keep the estate settlement process moving forward.