Conn. Gen. Stat. § 12-378

(b) The Commissioner of Revenue Services shall issue receipts in duplicate for all taxes paid or, if no tax is found due, a certificate that no tax is due, but shall not be required to issue a certificate that no tax is due whenever a judge of the probate court having jurisdiction of the estate of a deceased person issues an opinion as provided in subsection (a) of this section, and the commissioner has not filed an objection to such opinion. A copy of the final receipt or of such certificate, if any, that the commissioner is required to provide under this subsection, with the amount of the gross taxable estate shown thereon, shall be filed with the probate court and sent to the fiduciary or transferee and no representative of an estate shall be entitled to a final accounting unless such final receipt or such certificate, if any, that said commissioner is required to provide under this subsection, has been filed with the probate court. Such final receipt filed with the probate court shall be conclusive evidence that all real property included in the gross taxable estate is free from any claim for tax due the state under this chapter in respect to the interest of such deceased person in such real property.

Cited. 152 C. 338.