We use the credit report to determine the borrower's current debt obligations. Further, 1026.43(c)(3)(iii) gives the following guidance...
(iii) For purposes of paragraph (c)(2)(vi) (Borrower's DTI) of this section, if a creditor relies on a consumer's credit report to verify a consumer's current debt obligations and a consumer's application states a current debt obligation not shown in the consumer's credit report, the creditor need not independently verify such an obligation.
I checked with my underwriters, and they confirmed that they use the payment reported on the credit report as the 3rd party verification. If no amount is listed, than they use 2% of the outstanding balance (per FHLMC guidelines).