Thus far, we have only sent pre-lien notices to the taxpayer of each property. However, my understanding from reading another WA state construction lawyer blog is that we should be sending the notice to both the property owner and the prime contractor. Additionally, upon receipt of full payment, we're meant to send a lien release to both parties. Is this the case?
A Washington Notice to Owner should be sent to both the property owner and the prime contractor. You can learn more about Washington's preliminary notice requirements with these resource: Washington Preliminary Notice FAQs.
Regarding lien waivers: Yes, Washington construction businesses are required to waive lien rights if payment has been made. This is laid out at RCW § 60.04.071, which states "Upon payment and acceptance of the amount due to the lien claimant and upon demand of the owner or the person making payment, the lien claimant shall immediately prepare and execute a release of all lien rights for which payment has been made, and deliver the release to the person making payment." And, if a party unjustifiably withholds a lien waiver, they could face having to pay damages and attorney fees for others.