31/43, 37/47, 40/50: Decoding FHA Manual Underwriting Ratio Tiers

Start With the Numbers That Matter

31 and 43. If you've been digging into FHA debt-to-income rules, you've probably already run into these numbers and wondered where the flexibility actually is. There is some, but it depends entirely on two things: your credit score tier and whether your file lands in manual underwriting or TOTAL AUS.

Consider a situation that comes up often on manually underwritten FHA files: a borrower with a credit score in the high 500s, tight debt ratios, and a straightforward purchase, like a three-bedroom home. We'll use the example of Donna, a nurse near St. George, SC, to walk through how the tiers actually apply.

The Ratio Tiers, Verbatim

The governing language reads: "For manually underwritten Mortgages, maximum qualifying ratios depend on credit score and compensating factors: MDCS 500-579 or No Score: 31/43, no exceptions; MDCS 580+: 31/43 with no compensating factors, 37/47 with one compensating factor, or 40/50 with two compensating factors and no discretionary debt. For TOTAL AUS scored Mortgages, the DTI is evaluated as part of the overall risk assessment without a fixed cap. FHA does not use residual income as a primary measure like VA."

Notice the structure: it's not one cap, it's tiered. Score 500-579 gets zero flexibility - 31/43 is final. Score 580 and above opens three tiers depending on how many compensating factors you bring, and the top tier specifically requires no discretionary debt alongside two compensating factors.

Manual vs TOTAL: Why the Path Changes Everything

Here's the part borrowers researching this topic often miss: these fixed ratio tiers only apply to manually underwritten files. If your file runs through TOTAL AUS instead, the system evaluates DTI as one part of an overall risk assessment, with no fixed cap at all. Two files with identical ratios can land in completely different places depending on which path they take.

For a borrower in Donna's position - credit score in the high 500s - the file is very likely headed to manual underwriting, which means the 31/43 ceiling applies with no exceptions, full stop. Compensating factors don't move that number for scores below 580. They only start mattering at 580 and above.

What to Actually Ask Your Loan Officer

If you're sub-580 or your ratios are tight, ask this verbatim: is my file manual or TOTAL, and if it's manual, which compensating factors do I already qualify for under Section II.A.5.c.viii? That question forces a direct answer about which tier applies before you've spent time and money assuming a different outcome.

FHA also does not lean on residual income as a primary qualifier the way VA guidelines do, which makes these DTI tiers the main lever on this loan type. Understanding exactly where your score and file type place you is the single most useful thing you can do before submitting.

I'm Jason Sharon, licensed mortgage broker at Home Loans Inc. If you want your file reviewed against these tiers before you apply, reach out and I'll walk through exactly where you land.

Home Loans Inc - Jason Sharon, Mortgage Broker. Company NMLS #1728740, Jason Sharon NMLS #1281448. Equal Housing Opportunity.