The number on Zillow said $6,400 in annual property taxes. The seller’s disclosure backed it up. My lender used it. My preliminary budget used it. And if I hadn’t called the Travis County Appraisal District on a Tuesday afternoon out of pure habit, I would have closed on a house that was about to cost me several thousand dollars more per year than anyone’s spreadsheet was showing.

That’s the property tax trap. And it catches people constantly in Texas.

What “Last Year’s Taxes” Actually Means

When you’re underwriting a purchase — whether you’re an investor running cash-flow numbers or a first-time buyer trying to figure out what your PITI payment will be — you almost always get handed the prior year’s tax bill. It’s a real document. It’s accurate. And in Texas, it can be nearly meaningless as a forward-looking number.

Here’s the problem. Texas appraisal districts reassess values annually. If a home sold for $280,000 three years ago and the owner’s assessed value got frozen or capped near that number, the tax bill they’ve been paying might reflect something like $260,000 in taxable value. You buy that same house today at $390,000, and your assessed value next January could reset — not to $260,000, but somewhere much closer to what you actually paid.

The 10% homestead cap that people talk about? That only applies to owners who already have a homestead exemption in place and have owned the property for at least a year. It does not protect you in year one. The appraisal district can bring your value to market on the next assessment cycle, and “market” is exactly what you just told them you paid by signing a deed.

That gap between the seller’s tax bill and your future tax bill is the trap.

The Math Nobody Runs at the Kitchen Table

Let me put some rough numbers on this, because I think people hear “reassessment” and don’t feel it viscerally until they see what it does to a monthly payment.

Say you’re buying in Williamson County — somewhere in the Georgetown or Round Rock corridor, where the combined tax rate runs somewhere around 2.0% to 2.3% depending on the MUD and school district. Last I checked, some of those master-planned communities out near Ronald Reagan Boulevard were sitting with rates north of 2.4% once you stacked all the layers.

  • Seller’s taxable value: $265,000 → annual tax ~$6,100
  • Your purchase price: $385,000 → potential reassessed value $365,000–$385,000
  • Your annual tax at 2.2%: somewhere around $8,000–$8,500
  • Monthly difference: $160 to $200 more than your lender modeled

That’s not catastrophic on its own. But add that to a rate environment where your mortgage payment is already stretched, and it’s the kind of surprise that makes people feel like they were misled — even if nobody actually lied to them.

Property taxes are shaping up to be the affordability crisis that gets the least attention, and this reassessment timing issue is a big part of why.

Where It Gets Worse: New Construction and Recently Renovated Properties

I’d argue the trap is sharpest in two situations.

New construction is the one that bites investors and first-time buyers hardest. Builders often close homes before the appraisal district has fully assessed the improved value — sometimes the land is assessed, but the structure hasn’t been rolled in yet. Your first year’s tax bill looks almost reasonable. Year two is a different story entirely.

I’ve seen this out in the newer sections of Hutto and Kyle, where a buyer will close in the fall, get a tax bill that reflects only partial improvement value, and then get a sticker shock notice from the appraisal district the following spring. By then, they’ve already bought the furniture.

Renovated properties in Austin’s older neighborhoods — think the strips along Springdale, or the blocks between Airport and MLK on the east side — carry the same risk. A seller who bought and renovated might have held long enough for the cap to compress their assessed value well below market. You buy at their renovation-era price and the district recalibrates fast.

How to Actually Protect Yourself

This isn’t complicated, but it does require you to do a few things your lender probably isn’t going to do for you.

  1. Look up the property on the county appraisal district website yourself. Travis County is traviscad.org, Williamson is wcad.org, Tarrant is tad.org. Find the current assessed value and compare it to your purchase price.
  2. Calculate taxes at your purchase price, not the current assessed value. Use the actual rate for that specific jurisdiction — not a county average, because MUD rates, school district rates, and city rates all stack differently depending on exactly where the property sits.
  3. Ask your lender to model the payment both ways — once at the current tax bill and once at a projected reassessed value. Make sure you can afford the higher number.
  4. For new construction, ask the builder’s rep what the land-only assessment is and what the builder expects the improved value to come in at once the structure is fully assessed. Get it in writing if you can.
  5. File your homestead exemption the day you’re eligible. In Texas that’s January 1st of the year following your purchase, as long as it’s your primary residence. Don’t wait. The cap starts running from the date of that exemption.

If you’re an investor and you’re running rental yield numbers, add a full reassessment buffer into year two of your model. Assume the district is going to find you. They will.

One More Thing About Escrow Estimates

Your lender’s escrow estimate at closing is based on the current tax bill, padded slightly. It is almost never padded enough to absorb a full reassessment. That’s not the lender being sneaky — it’s just how escrow analysis works. What it means in practice is that you may get an escrow shortage notice in your first or second year, which results in either a lump-sum payment or a bump in your monthly payment going forward.

Plan for it now rather than being surprised by it later. The broader math problem with Texas housing costs keeps getting harder, and the tax piece is one of the few levers buyers can actually get ahead of if they do the work before signing.

Call your appraisal district. Run the higher number. Budget for the gap. It’s a Tuesday afternoon phone call that can save you a lot of Monday morning headaches.