20 CFR § 345.122 - Interest.
(a)Rate. If the employer's contribution is not paid to the Board when due and is not adjusted under § 345.118 of this part, interest accrues at the rate of 1 percent per month, or fraction of a month. Interest on past due contributions from the due date thereof until the date paid will be assessed after payment of the contributions, and notice and demand made upon the employer for payment thereof, in any case in which payment of the contribution is made before assessment under § 345.120.
(1) There was a reasonable cause and not willful neglect for the late filing, late payment or underpayment, such as: the serious illness or death of an individual with the sole authority to execute the return and payment; fire, casualty, or natural disaster at the place where the railroad unemployment insurance records are kept; or reasons outside the employer's control, such as, the failure of the employer's bank to comply with the employer's filing and payment instructions;
(2) The amount of interest attributed to the delinquency is totally disproportionate to the period of the delay and the amount of contributions paid; and
(3) The employer's past record for timely compliance with railroad unemployment insurance reporting and payment requirements warrants such action considering such factors as the number and extent of delays associated with late reports, payments, and underpayments.