by Dan Persfull:
(2) Basis for determination. Except as provided otherwise in paragraphs (d), (e), and (f) of this section, in making the repayment ability determination required under paragraph (c)(1) of this section, a creditor must consider the following:
(v) The consumer's monthly payment for mortgage-related obligations;
(8) Mortgage-related obligations mean property taxes; premiums and similar charges identified in ยง 1026.4(b)(5), (7), (8), and (10) that are required by the creditor; fees and special assessments imposed by a condominium, cooperative, or homeowners association; ground rent; and leasehold payments.
by Jim Bedsole:
Minor clarification: The provisions cited by Dan under 1026.43 only apply to certain consumer-purpose dwelling secured transactions. The original question is not clear on that point, mentioning only "new consumer loan". For calculation of DTI on a consumer loan NOT secured by a dwelling, what gets included in the "mortgage payment" would be a matter of loan policy for your institution. You will want to make sure you are applying whatever standard you choose consistently.