Not sure who your servicer is, but in 14 years in this business, I’ve never heard of a co-borrower not having a mortgage show up on their credit report. Someone on title but not loan, of course, but not co-borrowers. Even authorized users (not joint account holders) on credit cards typically have those accounts show up on their reports. I’m pretty sure they’d immediately report a late mortgage payment on your credit! Think I’d give the CFPB (Consumer Finance Protection Bureau) a call for their take on your situation. You might also sent a letter (with proof of delivery) to your servicer mentioning your concern that your credit report is not getting the benefit of the mortgage payment history, that its omission has the potential to harm your credit and cause you financial loss, and ask them to tell you in writing whether they will start reporting that account. Guessing they’d be a little hesitant to put that “policy” in writing for legal purposes.