Underwriting Airbnb income: AirDNA, host history, and the 12-month rule

A well-run short-term rental can gross two or three times the long-term lease on the same doors. The underwriting question is never whether that revenue is real — it's how to document it when there's no lease to point at. There are exactly three answers.

Three ways to document the income

1 · Host history (refinances). Twelve months of Airbnb or VRBO statements, gross receipts netted for platform fees, averaged into a monthly figure. Twelve months matters because it captures a full seasonal cycle — a Smoky Mountains cabin's December and its September are different businesses.

2 · Market projection (purchases). No operating history yet, so a data provider's rentalizer report — comparable listings, occupancy, ADR — stands in. We credit it at 80% to absorb ramp-up and optimism, and the projection has to come from the property's actual configuration, not the best cabin on the mountain.

3 · The 1007 floor. Every file also gets a long-term market rent opinion. If your deal only works on STR numbers, that's worth knowing before you buy; if it clears DSCR on the boring lease, the STR upside is pure margin.

The math on a real cabin

Same cabin on its long-term 1007 rent of $2,900 would squeak by at 0.80 — a no. The documentation path isn't paperwork; it's the difference between a deal and a decline.

What kills STR files

Three things, and none of them are revenue: permits — if the city or county requires an STR license, it's a closing condition, not a detail; HOA and zoning restrictions — a board that can vote out rentals next year is a lien on your income; and condotels — front-desk buildings with rental programs are a different asset class and price accordingly. Check all three before the earnest money goes hard.