Conn. Agencies Regs. § 12-2-11
(b) Failure to pay tax on time due to reasonable cause. A penalty will be waived, if a taxpayer clearly establishes the facts alleged to be a reasonable cause for failure to pay tax on time in the form of a written statement. The following are examples of a failure to pay tax on time due to reasonable cause:
(c) Failure to pay tax on time not intentional or due to neglect.A penalty will be waived, if a taxpayer clearly establishes the facts alleged to be a cause of the taxpayer's unintentional failure (and not a failure due to neglect) to pay tax on time in the form of a written statement. The following are examples of a failure to pay tax on time which is unintentional (and not due to neglect):
(Effective May 25, 1989)