Connecticut Form CT-706/709: Who Files It and What It Actually Costs

Most Connecticut estates never touch Form CT-706/709 — the state's estate and gift tax return for taxable estates. But if the gross estate exceeds $15 million, this form is where the real financial exposure lives. And unlike its counterpart, Form CT-706 NT (used for non-taxable estates), the CT-706/709 goes directly to the Department of Revenue Services (DRS), carries a 12% flat tax rate on everything above the exemption, and intersects with Connecticut's standalone gift tax in ways that catch even experienced estate attorneys off guard.

Here's a plain-English breakdown of who files this form, how it works, and the specific traps to avoid.

Who Must File Form CT-706/709

The CT-706/709 is required in two situations:

1. The gross taxable estate exceeds $15 million (the 2026 Connecticut estate tax exemption, indexed annually for inflation and now permanently aligned with the federal exemption).
2. The decedent made taxable lifetime gifts that must be reported under Connecticut's separate gift tax.

For estates below the $15 million threshold, the executor files Form CT-706 NT (Non-Taxable) with the Probate Court instead — but the CT-706 NT does not go to the DRS, and it imposes no estate tax.

The CT-706/709 is filed directly with the Connecticut DRS. A copy must also be provided to the Probate Court. The deadline is the same as for the non-taxable return: six months from the date of death.

The 12% Flat Rate and How It's Calculated

Connecticut taxes the amount of the estate that exceeds the $15 million exemption at a flat rate of 12%. There is no graduated bracket structure at the state level — any dollar above the threshold is taxed at 12%.

A simple example: an estate with a gross value of $17 million would pay 12% on the $2 million above the exemption, resulting in approximately $240,000 in Connecticut estate tax — in addition to any federal estate tax owed.

For the federal estate tax, the exemption in 2026 is also approximately $15 million per individual (subject to congressional action), and the marginal rate above the exemption can reach 40%. This means large Connecticut estates face a combined marginal rate of 52% on assets above the threshold — making estate planning on the front end extremely valuable.

The gross estate calculation for the CT-706/709 includes everything counted for federal purposes: solely owned assets, the decedent's share of jointly owned property, life insurance proceeds if the decedent owned the policy, qualified retirement accounts, and the full value of revocable living trust assets.

Connecticut's Gift Tax: The Only State-Level Gift Tax in the U.S.

This is where Connecticut stands completely alone. It is the only state in the country with a standalone gift tax. The Connecticut gift tax is unified with the estate tax — meaning the $15 million exemption applies to the combined total of lifetime taxable gifts and the taxable estate.

The annual gift exclusion mirrors the federal amount: $19,000 per recipient in 2026. Gifts within this annual exclusion don't count toward the lifetime exemption. But gifts above the annual exclusion made during the decedent's lifetime must be reported on the CT-706/709 and applied against the remaining lifetime exemption.

This creates a significant complication for executors. To complete the CT-706/709 accurately, you must locate all prior Connecticut gift tax returns (Form CT-709) filed by the decedent. If the decedent made large gifts in prior years and no CT-709 was ever filed — a common oversight — the executor may need to reconstruct the gift history to calculate the remaining exemption accurately.

The No-Portability Problem

The most consequential difference between Connecticut's estate tax and the federal estate tax is the absence of portability.

Under federal law, a surviving spouse can elect to use the deceased spouse's unused federal estate tax exemption (DSUE). If one spouse dies having used none of their $15 million exemption, the survivor can potentially shelter up to $30 million from federal estate tax. This election requires filing IRS Form 706 within nine months of death, but the benefit is substantial.

Connecticut does not allow this. A surviving spouse cannot inherit the deceased spouse's unused $15 million Connecticut exemption. It simply disappears.

For wealthy couples, this means that relying on portability — which works fine at the federal level — will leave the Connecticut estate fully exposed on the second death. The standard solution is a Credit Shelter Trust (also called a Bypass Trust): on the first death, the trust is funded up to the exemption amount, preserving the first spouse's $15 million state exemption for the benefit of heirs rather than letting it evaporate. The surviving spouse has access to income from the trust without it being included in their taxable estate.

If a couple is in the $15–30 million range and has not structured their estate around this Connecticut-specific gap, the second death could trigger $1.8 million in avoidable Connecticut estate tax (12% on $15 million).

Key Deductions That Reduce the Taxable Estate

The CT-706/709 allows several deductions that can reduce the amount subject to tax:

• Marital deduction: Assets passing outright to a surviving U.S. citizen spouse are generally deductible from the gross estate. However, given Connecticut's no-portability rule, this deduction can be a double-edged sword — it lowers the first spouse's taxable estate but potentially increases the second spouse's.
• Charitable deduction: Assets left to qualifying charities are fully deductible.
• Debts and expenses: Outstanding mortgages, final medical bills, funeral expenses, and estate administration costs (including attorney and executor fees) are deductible.
• State death taxes paid elsewhere: If the estate includes real property or business interests in another state that imposes its own estate or inheritance tax, a deduction may be available.

The interplay between these deductions and the federal return (IRS Form 706) is intricate. Most estates at this size will work with an estate attorney and CPA in tandem.

Form CT-706/709 vs. CT-706 NT: Quick Comparison

The Real Estate Lien Still Applies

Whether you're filing the CT-706 NT or the CT-706/709, the inchoate Connecticut estate tax lien applies the same way. The state's lien attaches automatically to all Connecticut real property at the moment of death and remains until the lien release certificate is obtained and recorded with the Town Clerk.

For CT-706/709 filers, the DRS issues the release after the tax is paid and the return is accepted. The probate fee under C.G.S. § 45a-107 also still applies to estates subject to the CT-706/709, calculated against the gross taxable estate up to the $40,000 statutory cap.

When to Involve Professionals

For the vast majority of Connecticut estates — those well below $15 million — the CT-706 NT process is manageable with careful preparation. But estates reaching the CT-706/709 threshold involve a level of complexity that makes professional guidance worth the cost:

• A Connecticut estate attorney is essential for marital deduction planning, Credit Shelter Trust setup, and navigating the absence of portability.
• A CPA with estate experience handles the form itself, the interplay with IRS Form 706 and 1041, and the gift tax reconstruction.
• A certified appraiser provides defensible date-of-death valuations for real estate and business interests, which the DRS can and does audit.

Whether your estate falls under the CT-706 NT or the CT-706/709, clearing the Connecticut tax obligations is the unlock that lets everything else proceed — the lien release, the asset distributions, the real estate closing. The Connecticut Final Tax & Estate Tax Guide covers both forms, the probate fee calculation, and the full executor tax checklist in one place.

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