As per the Presidential Decree numbered 5801 published in the Official Gazette dated 21 July 2022 and numbered 31899, the monthly default interest rate regulated under Article 51/1 of the Law on the Collection Procedure of Public Receivables for the portion of the public receivable that is not paid within the payment period, which will be applied separately for each month from the due date, has been increased from 1.6% to 2.5% per month.

Please see this link for the full text of the Presidential Decree (only available in Turkish).