You should contact a collection agency to attempt to collect the payment. They will report the non paymnet to the credit bureaus and normally take their fees out of what they may collect on your behalf. You can’t directly report the non payment yourself. The credit bureau will also do all of the work to try and recover any moneys due to you. Just make sure you are very serious about this! The credit bureau will hound thses people and putting this on their credit record may cause them serious harm for a long time. A better solution may be to take them to small claims court or hire an attorney that specializes in collections. Many will also take their fees from whatever they collect and can ask a court to have the tenants ordered to repay you on a schdule or garnish their wages untill you are paid in full.