Property tax after reassessment on transfer, and why the listing's tax number is not yours

Here is a deal that works on paper and does not work in reality.

A property listed at $185,000. The listing sheet shows $2,650 in annual property tax. You enter $2,650, the model returns positive cash flow, and you offer.

Then the first bill arrives at $4,100.

Nothing was calculated wrong. The number was simply not yours to use.

What actually happens on transfer

An assessment is the county's opinion of what a property is worth for tax purposes. It is not the sale price, and in many counties it has not been revisited in years.

When the property sells, most jurisdictions reassess. The sale is a fresh, arm's-length data point about what the property is worth, and the county uses it. The new assessment is based on what you paid, not on what the last owner was assessed at.

So the seller's tax line tells you about the seller. It tells you almost nothing about your first year.

Why it is the most expensive line to miss

Two reasons.

It is large. Tax is one of the biggest operating expenses on a small residential deal, often second only to debt service. A doubling is not a rounding error.

And it is permanent. A bad rehab estimate hurts once. A tax figure that is wrong by $1,450 a year is wrong every year you own the property, and it is wrong again in the resale numbers when you eventually sell to someone who underwrites it correctly.

How to get the real number

Three steps, and none of them require a subscription.

Find the assessment ratio. Counties assess at a percentage of market value, and it is published. Some assess at 100 percent, many do not.

Find the millage or tax rate. Also published, usually as the sum of county, municipal and school district rates. The school district portion is often the largest and the one people forget to include.

Apply both to your purchase price, not to the current assessment.

That is: purchase price, times the assessment ratio, times the millage rate. If your county reassesses on transfer, that figure is a far better estimate of your first full year than anything printed on the listing.

The exceptions, because they are real

Not every jurisdiction reassesses on sale, and the ones that do not are worth knowing about.

Some states cap how fast an assessment can rise regardless of sale price. Some reassess on a fixed cycle rather than on transfer. A few have homestead or owner-occupancy provisions that you lose as an investor even where the assessment itself does not move, which produces the same effect through a different mechanism.

There are also abatements and exemptions attached to the current owner rather than to the property. Those end with the sale.

So the instruction is not "double the tax." It is: find out what your specific county does, before you offer. The rule varies. The arithmetic does not.

What to ask, and who to ask

Call the county assessor and ask two questions.

Does an arm's-length sale trigger a reassessment here, and on what schedule.

What is the current assessment ratio and total millage for this parcel's district.

They answer this every day. It is a five minute call and it is the highest-return five minutes in the whole underwriting process.

The wider point

This line is the clearest example of the thing that kills first deals. The number on the listing was not wrong. It was accurate, sourced, and completely irrelevant to you.

A model cannot tell the difference. It takes what you type. Which is why the useful question when you look at a pro forma is never "are these numbers right." It is "whose numbers are these."