The listing says the annual property taxes are 4,500 dollars. You build the deal on 4,500 dollars, the coverage ratio comes out at 1.18, and you write the offer. Eleven months after closing a tax bill shows up for 7,800 dollars, your escrow account is short by most of a payment, and the servicer raises your monthly by 275 dollars to catch up.
Nothing went wrong with the property. The number on the listing was true, and it was the wrong number for you. It was the seller’s tax bill, calculated with an owner occupant exemption you will never receive and, in many places, on an assessment that had been frozen for years and resets the moment the deed records.
This is the single most common modeling error investors make on a first bill, and it is entirely avoidable. Here is what the exemption does, how much it moves, why some lenders catch it and some do not, and how to get the real number before you are committed.
The number on the listing is the seller’s number
Property tax data on a listing, in a tax portal, or on a county parcel page is almost always the current year’s billed amount for the current owner. It reflects every benefit that owner qualifies for. If the seller lived in the house, that typically includes some form of owner occupant relief, which goes by different names depending on where the property sits: a homestead exemption, a homestead exclusion, a principal residence exemption, an owner occupant credit.
The mechanics differ but the direction never does. The program reduces the taxable base, or reduces the rate, or caps how fast the assessment can climb, and all three of those benefits attach to the owner rather than to the building. When an investor buys, they come off. You are not being penalized. You simply are not eligible, because you do not live there.
What makes this expensive is timing. The change usually does not appear on a bill until the next full assessment cycle, which can be eight to eighteen months after you close. So your first year or so looks exactly like your model, you conclude the model was right, and then the correction arrives all at once. The assessment reset that follows a purchase is covered in more depth in property tax reassessment after purchase, and the exemption question sits directly on top of it.
What the exemption actually does to the bill
Run it as arithmetic. Say the county assesses the property at 200,000 dollars and the combined millage is 30 mills, which is 30 dollars of tax for every 1,000 dollars of taxable assessment.
The seller is an owner occupant with a 50,000 dollar homestead exclusion. Their taxable assessment is 150,000 dollars, and their annual bill is 150,000 times 0.030, or 4,500 dollars. That is the number on the listing, and it is 375 dollars a month.
You buy it as a rental. The exclusion comes off, so your taxable assessment is the full 200,000 dollars and your bill is 6,000 dollars a year, or 500 dollars a month. The exemption alone cost you 125 dollars a month, which is 1,500 dollars a year, every year you own the building.
That is before anyone reassesses anything. The exclusion is a straightforward subtraction and it is the easy half to estimate: find the exclusion amount, add it back to the taxable assessment, multiply by the millage. Any county assessment office will give you both figures, and most publish them. The hard half is what happens to the assessment itself.
The assessment cap is the bigger half
Many jurisdictions pair owner occupant relief with a limit on how fast an assessment can rise while the same owner holds the property. A seller who has owned for fifteen years may be assessed far below what the house is actually worth, not because anyone made a mistake, but because the cap worked exactly as designed.
A sale almost always lifts that cap. The property gets reassessed toward current market value, and the new owner starts from there. So the investor buying that fifteen year hold absorbs two increases at once: the exemption coming off, and the assessment climbing to market.
Continue the example. The capped assessment was 200,000 dollars, but the property just sold for 260,000 dollars and the county reassesses to the sale price. Your taxable assessment is 260,000 dollars with no exclusion, and your bill is 260,000 times 0.030, or 7,800 dollars a year. That is 650 dollars a month against the 375 dollars on the listing.
The bill did not go up by a third. It went up by 73 percent, and the seller’s number was never a forecast of anything. This is the mechanism behind most of the ugly escrow surprises investors describe in their second year of ownership.
The worked example: 1.18 becomes 1.02
Now put it through a loan file. The rent is 2,100 dollars a month. You are borrowing 185,000 dollars on a thirty year fixed at 7.25 percent, which is roughly 1,262 dollars of principal and interest. Landlord insurance runs 1,680 dollars a year, or 140 dollars a month.
Underwrite it on the seller’s tax figure and the housing payment is 1,262 plus 375 plus 140, or 1,777 dollars. Coverage is 2,100 divided by 1,777, which is 1.18. Comfortable.
Underwrite it on your actual first full bill, with the exclusion gone and the assessment reset, and the payment is 1,262 plus 650 plus 140, or 2,052 dollars. Coverage is 2,100 divided by 2,052, which is 1.02. On a program with a 1.10 minimum that is a decline, on identical rent and an identical loan.
The gap between those two ratios is one data entry decision. If you want to see what it does to a specific deal, put both tax figures through the DSCR deal calculator and compare, and if the denominator itself is unfamiliar, the full explanation of how coverage is calculated shows exactly where the tax line enters.
Whether the lender catches it, and why that is not good news
Some lenders underwrite the forward looking bill. They will estimate the post sale assessment, strip the exemption, and build the payment from that. Others take the current billed amount off the tax certificate and move on.
It is tempting to hope for the second kind. It is the worse outcome. A loan approved on the seller’s tax number is a loan whose escrow was funded on the seller’s tax number, and the shortage does not disappear because nobody predicted it. It lands on you fourteen months later with the whole annual gap plus the reserve the servicer now needs, spread over twelve payments. The way that recalculation works is laid out in escrow analysis and shortage, and the arithmetic is unforgiving.
A lender that underwrites the real number is telling you something useful before you are committed: this deal is thinner than you thought. You can renegotiate, put more down, or walk. A lender that does not is leaving the discovery until you have no options left.
So do not treat a lender’s willingness to use the low figure as a win. Do the forward calculation yourself regardless of which kind of lender you are working with, and decide whether you want the deal at the real payment.
The other charges riding on the same bill
While you are pulling the real tax picture, pull everything else printed on that bill, because the property tax line is rarely alone on it.
A sewer, street, or sidewalk charge levied against the parcel shows up there and runs for a fixed number of years, which is the issue in the special assessment on the tax bill. Energy financing attached to the parcel does the same thing and can sit ahead of your mortgage in priority, which is the problem in a PACE assessment on the tax bill.
A property that straddles a municipal line gets two bills under two sets of rules, and the escrow is frequently set up wrong from day one. That is the situation in a rental sitting in two townships. And an abatement that is partway through a phase out is a scheduled increase hiding in plain sight, described in the tax abatement that burns off.
Unpaid balances are their own category. Water and sewer arrears attach to the real estate and follow it to you, as in the municipal lien that follows the property, and the closing side of all of this sits in transfer tax, recording fees, and municipal liens.
How to get the real number before you offer
This takes one phone call and about fifteen minutes, and it is the highest return fifteen minutes in the whole acquisition.
Call the county assessment office and ask four questions. What is the current taxable assessment, and does it include an owner occupant exclusion or credit. What is the exclusion worth. What is the combined millage for this parcel, including school and municipal. And does a sale trigger a reassessment, on what timetable.
Then do the arithmetic yourself: take the assessment, add back the exclusion, substitute the sale price if a sale triggers a market reset, multiply by the millage, divide by twelve. That number goes in your model. Not the listing figure, not the seller’s bill, not last year’s tax certificate.
Build the deal on it and keep the escrow. On a net lease where the tenant is contractually covering the taxes, keeping the impound is the only thing that tells you promptly if the tenant stops paying, which is one of the reasons the structure in net leases and the DSCR a lender will actually use gets built the way it does. The general case for and against impounds sits in escrow and impounds on a rental loan and escrow waivers.
What to do if you already closed on the wrong number
If the bill has already arrived and the escrow is short, you have a cash flow problem rather than a loan problem, and there are three things worth doing in order.
First, read the assessment notice for the appeal deadline, which is usually short and usually printed in small type. If the county reassessed to the sale price and your purchase included anything other than the real estate, or the sale was not an arm’s length transaction, there may be a legitimate basis to contest the figure. Second, ask the servicer for the shortage spread over the longest period they allow rather than the shortest, which softens the monthly hit. Third, if the shortage was large enough to push you below your own cash flow floor, run a refinance analysis before the next cycle rather than after it.
Also note that none of this shows up in the consumer disclosure package you may be expecting, because a rental loan does not generate one, which is the point of why a DSCR loan skips the consumer forms. Nobody is going to hand you a projected payment sheet. You have to build it.
If you have a property under agreement and want the forward tax figure checked before your contingency runs out, send us the address and the parcel number and we will run the real payment. Call 412-990-2941 if the clock is short.
FMC Capital is a Pittsburgh-based mortgage brokerage, NMLS #1840537. We place loans on rentals and flips across Pennsylvania and additional states. Assessment practices, exemption programs, millage, and reassessment timing vary by county and are subject to change. Loan terms and coverage minimums vary by lender. Nothing here is a commitment to lend, and nothing here is legal or tax advice. Confirm assessment figures with the county and consult a qualified professional on any appeal.