Up until July 28, 2019 motorcycle insurance was not mandatory but effective July 28, 2019 Washington State passed a new law that all motorcycle drivers must carry liability insurance and proof that you have insurance.
The state minimum motorcycle liability limits that are required are the same as the car insurance liability limits of:
$25,000 for injuries per person in another vehicle
$50,000 for total injuries per accident
$10,000 for damage to another person’s property