REV 27-0036
A firm asks a customer for this certificate, the buyer fills in and signs the form from the emailed link, and Sundry shows it signed and Verified by Sundry.

Farmers pay no Washington sales or use tax on propane or natural gas used only to heat barns and sheds that house only chickens sold as agricultural products. The test is "exclusively" twice over: the fuel only heats the chicken houses, and the buildings only house chickens. Gas for incubation rooms, egg rooms or the farmhouse stays taxable.
Form REV 27 0036 (revision 7/13/23), Section B line 4a: "Propane or natural gas used to heat structures used to house chickens." The instructions add: "The chickens must be raised by a farmer and sold as agricultural products." Because propane is usually delivered on a recurring schedule, a blanket certificate fits. The signature block asks for Account ID (if applicable), type of entity, name of buyer, farm name, mailing address, authorized signature, date, title and phone number. By signing, the buyer states it qualifies, that it "must keep records to verify the exempt nature of the sale," and that misuse "will result in taxes due, applicable interest, and possible penalties." The form has no field for the seller's name. The buyer ticks single use or blanket; a blanket certificate stays valid while there is at least one sale within 12 months. Cannabis growers and producers cannot use the form.
RCW 82.08.910(2): "The seller must retain a copy of the certificate for the seller's files." Form REV 27 0036 says the seller "must retain the original of this certificate for their records" and must not send a copy to the Department, and: "A seller who accepts this completed certificate is relieved of the responsibility to collect retail sales or use tax unless the seller fraudulently fails to collect the tax or solicits the purchaser to participate in unlawfully claiming the exemption." The certificate does not expire while buyer and seller have at least one sale within twelve consecutive months; after a longer gap the seller must obtain a new form. WAC 458-20-210(10): "Without proper documentation, sellers are liable for payment of the retail sales tax on sales claimed as exempt." RCW 82.32.070(1) requires records to be kept for five years, and RCW 82.08.050(7)(a)-(b) gives the 90-day and 120-day windows for obtaining a fully completed certificate.