Interest is calculated based upon the outstanding principal at the beginning of each billing year. Interest is billed annually and is assessed in full on the first day of each billing year. Any payoff of an assessment after the annual billing will be charged a full year’s interest (RCW 35.49.050).
Example: Due date is May 1 and the required minimum payment is made on May 1. Then on July 1, resident is able to pay off. Even though only 2 months have passed, a full year of interest is still charged.