Wash. Rev. Code § 50.24.040
If contributions are not paid on the date on which they are due and payable as prescribed by the commissioner, the whole or part thereof remaining unpaid shall bear interest at the rate of one percent per month or fraction thereof from and after such date until payment plus accrued interest is received by him or her. The date as of which payment of contributions, if mailed, is deemed to have been received may be determined by such regulations as the commissioner may prescribe. Interest collected pursuant to this section shall be paid into the administrative contingency fund. Interest shall not accrue on contributions from any estate in the hands of a receiver, executor, administrator, trustee in bankruptcy, common law assignee, or other liquidating officer subsequent to the date when such receiver, executor, administrator, trustee in bankruptcy, common law assignee, or other liquidating officer qualifies as such, but contributions accruing with respect to employment of persons by any receiver, executor, administrator, trustee in bankruptcy, common law assignee, or other liquidating officer shall become due and shall draw interest in the same manner as contributions due from other employers. Where adequate information has been furnished the department and the department has failed to act or has advised the employer of no liability or inability to decide the issue, interest may be waived.
RCW 50.24.040
Conflict with federal requirements-Severability-Effective date-1987 c 111: See notes following RCW 50.12.220.
Effective date-1973 1st ex.s. c 158: See note following RCW 50.08.020.