PITIA breakdown: five inputs to verify in a DSCR scenario

A DSCR scenario divides expected monthly rent by the full monthly housing payment. That payment is PITIA: principal, interest, taxes, insurance, and association dues. Any modeled coverage ratio is only as reliable as those five inputs, and each one arrives from a different source with its own way of going wrong.

The ratio is a fraction built on five documents. If one of them is stale or guessed, the arithmetic still runs; it just runs on fiction. For each input, you want three things: where the number should come from, how an error in it moves the ratio, and the question that confirms it with the responsible provider who would actually underwrite the loan.

Principal and interest: set by the loan terms

Principal is the part of the payment that reduces the loan balance; interest is the lender's charge on that balance. Both come straight from the loan amount, rate, and amortization structure, meaning the schedule by which the balance is paid down over time, which makes them only as real as the quote behind them. An interest-only period changes the qualifying question entirely, because some program designs qualify on the interest-only payment and others on the fully amortizing one, and only the provider can say which applies to a given file. Assume a rate the provider never offered and the entire ratio drifts with it.

Taxes: the input most likely to be stale

Taxes pulled from a listing or an old statement can reflect the seller's assessed value, the value the county taxes, rather than the reassessment a sale may trigger in that county. A scenario built on last year's bill overstates coverage the moment the assessor updates its records. Two things to confirm: the county assessor's current figures, and the provider's policy on qualifying with projected versus current taxes.

Insurance: quotes, not placeholders

The insurance figure should come from an actual quote for landlord coverage on that specific property, not a rounded guess. Flood zone status, roof age, coastal exposure, and short-term-rental use each move the premium, and the provider may require coverage features the cheapest quote lacks. The companion post on insurance inside PITIA covers what those requirements can include.

Association dues: easy to omit, painful to discover late

Condo and HOA dues belong in the qualifying payment even though the association, not the loan servicer, bills them. The common misses are the extras: special assessments and master-association fees layered on top of base dues. The source that survives underwriting review is the association's current budget and fee schedule, confirmed in writing.

One error, one ratio: an illustrative walkthrough

Illustrative example: one stale tax line moves modeled coverage from about 1.30x to about 1.18x on the same $2,500 rent.

Walk the arithmetic, in this illustrative example only. Modeled rent is $2,500, and suppose the five PITIA inputs sum to $1,920 per month. Divide: $2,500 ÷ $1,920 is roughly 1.30x. Now suppose the tax line was stale and the correct figure is $200 higher. The payment becomes $2,120, and because the payment sits in the denominator, anything that raises it pulls the ratio down: $2,500 ÷ $2,120 is roughly 1.18x.

Scenario	Modeled rent	Total PITIA	Modeled coverage
As first modeled	$2,500	$1,920	≈ 1.30x
Tax line corrected (+$200)	$2,500	$2,120	≈ 1.18x

Nothing about the property changed. One unverified input did. Whether either number qualifies, and at what terms, is entirely the provider's decision.

Five questions to verify, one per input

Principal and interest: which rate, amortization structure, and qualifying payment (amortizing or interest-only) does the provider actually use for this scenario?
Taxes: does the provider qualify on the current tax bill or on a projected post-sale reassessment, and whose figure governs?
Insurance: what coverage types, limits, and deductibles must a quote include before it counts?
Association dues: any special assessments or master-association fees beyond the base dues, per the association's own documents?
The ratio itself: what coverage does this provider require for this property type and loan purpose, and how must the rent be evidenced?

A DSCR ratio is arithmetic; the five numbers underneath it are homework.

Five components, five sources, one direction of travel: raise any of them and the coverage ratio falls. Knowing where the trustworthy version of each number lives is what turns a provider conversation from a quote request into a verification, one question per input.