Retail businesses in WA will have received this recent notice from our Department of Revenue:
Starting July 1, 2019, retailers can no longer make tax exempt sales to nonresidents based on their residence (i.e. Alaska, Oregon, Montana). Instead, consumers residing in qualifying states, US territories or provinces of Canada may request a refund of state sales tax paid from the Department once a year. Please see our Special Notice for more information. https://dor.wa.gov/find-taxes-rates/retail-sales-tax/sales-nonresidents
I can only assume they are trying to accumulate less paperwork by asking eligible customers to keep track and submit only once a year. Thank you for your understanding. AEB 😉