Washington Revised Code Title 72. State Institutions § 72.76.020. Costs and accounting of offender days

(1) The costs per offender day to the sending jurisdiction for the custody of offenders transferred according to the terms of this agreement shall be at the rate set by the state of Washington, office of financial management under RCW 70.48.440, unless the parties agree to another rate in a particular transfer. The costs may not include extraordinary medical costs, which shall be billed separately. Except in the case of prisoner exchanges, as described in subsection (2) of this section, the sending jurisdiction shall be billed on a monthly basis by the receiving jurisdiction. Payment shall be made within thirty days of receipt of the invoice.

(2) When two parties to this agreement transfer offenders to each other, there shall be an accounting of the number of “offender days.” If the number is exactly equal, no payment is necessary for the affected period. The payment by the jurisdiction with the higher net number of offender days may be reduced by the amount otherwise due for the number of offender days its offenders were held by the receiving jurisdiction. Billing and reimbursement shall remain on the monthly schedule, and shall be supported by the forms and procedures provided by applicable regulations. The accounting of offender days exchanged may be reconciled on a monthly basis, but shall be at least quarterly.