Take a look at 1026.43(e)(5) for the rules you need to follow as a lender making loans under the small creditor portfolio option. You will not need to use Appendix Q, but you will need to consider DTI as outlined in 1026.43(e)(5)(i)(B). Also, you will not have to abide by the 43% DTI cap if you are using the small creditor portfolio QM option. Here’s a link to 1026.43 (the commentary is also a good place for additional information):
https://www.ecfr.gov/cgi-bin/text-idx?SID=d7bde6371e95b688a396f863c3ddd6f3&node=20130612y1.42
