Okla. Stat. tit. 12A, § 4A-506
(b) If the amount of interest is not determined by an
agreement or rule as stated in subsection (a) of this section, the amount is calculated by multiplying the applicable Federal Funds rate by the amount on which interest is payable, and then multiplying the product by the number of days for which interest is payable. The applicable Federal Funds rate is the average of the Federal Funds rates published by the Federal Reserve Bank of New York for each of the days for which interest is payable divided by three hundred sixty (360). The Federal Funds rate for any day on which a published rate is not available is the same as the published rate for the next preceding day for which there is a published rate. If a receiving bank that accepted a payment order is required to refund payment to the sender of the order because the funds transfer was not completed, but the failure to complete was not due to any fault by the bank, the interest payable is reduced by a percentage equal to the reserve requirement on deposits of the receiving bank.
Oklahoma Code Comment
With respect to Official Comment 2, Oklahoma law dealing with restitution and unjust enrichment should support that the
originator's bank should pay interest on any refund of payment.
If the
receiving bank is obligated to pay interest, the rate may be set by funds transfer system rule if the payment order was transmitted through the system.
Laws 1990, SB 641, c. 110, § 37, eff. July 1, 1991.