Conn. Gen. Stat. § 52-81

Upon the withdrawal of any civil action after it has been returned to court and entered upon the docket, and after an appearance has been entered for the defendant, a judgment for costs, if claimed by him, shall be rendered in his favor, but not otherwise. Judgment for costs shall not be rendered after the expiration of six months from the date of the withdrawal and no costs may be allowed which accrued after actual notice in writing of the withdrawal was given by the plaintiff to the defendant or his attorney, unless good reason therefor is shown to the court.