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.
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 $250, or more than $50 and it has been outstanding for over 30 days. RCW 42.17A.240(8).
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.