How PITIA Is Calculated — the Real Monthly Number a DSCR Loan Underwrites

The five pieces, one at a time

Principal and interest come straight from an amortization calculation based on loan amount, rate, and term — this is the part every mortgage calculator gets right. The other three pieces are where PITIA becomes more than a basic mortgage payment.

• Property taxes: usually estimated from the local assessed value or the purchase price times the county's mill rate, then divided by 12.
• Homeowners insurance: an annual premium quote divided by 12 — often higher for STR-zoned or coastal/wildfire-exposed properties.
• Association dues: the full monthly HOA, condo, or co-op fee, counted dollar for dollar, with no partial credit.

Why the gap between P&I and PITIA changes the ratio more than people expect

It's common for a buyer to mentally anchor on the P&I figure quoted early in a conversation, then be surprised when the DSCR comes back lower than expected. The gap is almost always taxes, insurance, or HOA — and in STR-heavy or coastal markets, insurance alone can add several hundred dollars a month that a generic online calculator never accounted for.

Escrow accounts are how a lender actually collects the tax and insurance pieces monthly instead of billing them as one annual lump sum — the mechanics of that are covered separately in escrow and impounds on a DSCR loan.

Getting an accurate PITIA before you run the ratio

The most reliable inputs are a real insurance quote for the specific property type (STR coverage is priced differently than standard landlord coverage) and the actual current tax bill or assessed value, not a rough percentage guess. HOA dues should come from the HOA's current fee schedule, since increases happen more often than buyers expect.