On a purchase money, homestead secured 30 year mortgage, is there anything in Texas law to preclude the following payment schedule: An annual fixed P&I payment for years 1-3. Years 4-30 will change to monthly P&I payments. The rate is fixed and the loan will be fully amortizing.
Supposedly the borrower with pay it off in the first two years or so, hence the request for annual payments the first three years.

Makes the DTI calculation a little more tricky, but I don't know of anything in Texas law that would prevent it on a purchase transaction.