Conn. Agencies Regs. § 31-244-4a
In order to be considered timely for purposes of Section 31-241 and Section 31-273(k) of the Connecticut General Statutes, an employer's response to the Administrator's notice of a fact-finding or request for information on a claim for unemployment compensation benefits shall be actually received in the manner and within the time frame prescribed by the Administrator in the notice of fact-finding or request for information. Nothing in this section precludes consideration of a late response received before an eligibility determination is made, or subsequent to such determination in the Administrator's exercise of continuous jurisdiction under Section 31-243 of the Connecticut General Statutes. However, such consideration shall not relieve the employer of any charges imposed pursuant to Section 31-241 or 31-273(k) of the Connecticut General Statutes as a consequence of untimely response, unless good cause for such late participation is shown. For purposes of this section, "good cause" means (1) agency error, or (2) circumstances beyond the employer's or its agent's control which could not have been reasonably foreseen or prevented.
Conn. Agencies Regs. § 31-244-4a