Agreement extending time for assessing deficiency or claiming refund

(a) If, within the time prescribed in § 12-733(a)-1 of this Part for the assessment of a deficiency, a written agreement between the Department and a taxpayer has been executed, extending the time during which a deficiency may be assessed with respect to a taxable year, then a claim for refund may be filed with respect to such taxable year during the time within which a deficiency may be assessed pursuant to such agreement. For purposes of this section, where a joint Connecticut income tax return has been filed, both spouses shall sign the written agreement to extend the time during which a deficiency may be assessed or a claim for refund may be filed.