You will report the gross annual income relied upon in making the credit decision for the individual applicant. Because the co-applicant is not a natural person, you would not report income for the co-applicant.
HMDA Appendix A states the following:
6. Income. Enter the gross annual income that your institution relied on in making the credit decision.
a. Round all dollar amounts to the nearest thousand (round $500 up to the next $1,000), and show in thousands. For example, report $35,500 as 36.
b. For loans on multifamily dwellings, enter “NA.”
c. If no income information is asked for or relied on in the credit decision, enter “NA.”
d. If the applicant or co-applicant is not a natural person or the applicant or co-applicant information is unavailable because the loan has been purchased by your institution, enter “NA.”