Washington Revised Code Title 6. Enforcement of Judgments § 6.36.140. Interest and costs

When a registered foreign judgment becomes a final judgment of this state, the court shall include as part of the judgment interest payable on the foreign judgment under the law of the state in which it was rendered, and the cost of obtaining the authenticated copy of the original judgment. The court shall include as part of its judgment court costs incidental to the proceeding in accordance with the law of this state.