All monetary contributions received from PACs, political parties and caucus political committees must be by written instrument (e.g., check, money order, cashier’s check). Those from individuals, associations, unions or businesses must be by written instrument if the contribution is more than $100. RCW 42.17A.475.
Bitcoin and other cryptocurrency should be treated as the equivalent of cash and limited to $100. The cryptocurrency should be converted to legal tender, deposited in the campaign depository within five business days of receipt (RCW 42.17A.220), and timely reported. If cryptocurrency is paid directly to a vendor for goods or services, it should be disclosed as an in-kind contribution using the fair market value of the cryptocurrency at the time the payment is made. The in-kind contribution must be timely and accurately reported by the recipient, including the name and address of the vendor.
Cash contributions must be deposited into the campaign bank account, and not spent directly or mingled with petty cash. Monetary contributions are required to be deposited into the campaign account within five business days of receipt.
According to state law, no expenditure may legally be made unless it's authorized by the candidate or a person named on the candidate’s C-1 registration. Campaign treasurers are also required to maintain a complete record of all expenditures, including obligations that have not yet been paid by the campaign. Further, the requirement to report all expenditures extends to outstanding debts. Each unpaid obligation must be reported as part of C-4 filings, in Part 3 of Schedule B, if it is (or is estimated to be) more than $750 and have been outstanding for more than five business days in the 30 days before an election, or have been outstanding for more than 10 business days during all other times RCW 42.17A.240(8). Regularly recurring expenses of the same amount (such as rent, utilities, insurance, cellular phone costs and payments to campaign staff) do not have to be reported unless they were past due on the last day of the reporting period.
If the campaign makes expenditures of over $50 in cash, rather than by check, be sure to obtain a receipt signed by the vendor and the treasurer or candidate and keep it as part of your records. PDC recommends that cash transactions be kept to a minimum. RCW 42.17A.425.