Property tax is the second-largest line in most monthly housing costs and the one most often misunderstood at purchase. The listing tells you what the seller paid. That number is rarely what you'll pay.
How property tax actually works
Property tax = assessed value × millage rate (or effective rate). Both pieces vary by jurisdiction, both update over time, and both can produce surprises after a sale.
Assessed value
This is what the county tax assessor thinks the home is worth. It's revisited annually in most states and tied — loosely or tightly, depending on the state's rules — to market value. In Texas, the appraised value is reset by the central appraisal district each year; homestead protection caps annual increases at 10% (or 20% under recent rule changes for non-homestead) but does not cap the reset that happens at sale.
Effective rate
The combined rate from all overlapping taxing authorities — county, city, school district, special districts (MUDs, PIDs, hospital districts). In Frisco, the all-in effective rate runs roughly 2.0–2.3%, depending on which school district and whether MUD/PID assessments apply. The school district piece is usually the largest.
The post-purchase reset
This is the part that catches buyers. The seller's tax bill reflects the seller's basis — when they bought, what protections accumulated, what exemptions applied. After the sale, the appraisal district resets the assessed value at or near the purchase price, and your tax bill jumps with it.
Worked example
- Seller bought in 2014 for $245,000. Homestead-capped at 10%/year, current assessed value sits at $338,000. At 2.1% effective rate, the seller's tax bill is $7,098/year, or $592/month.
- You buy in 2026 for $425,000. The appraisal district resets the assessed value to $425,000. At the same 2.1% rate, the new tax bill is $8,925/year, or $744/month.
- The delta is $1,827/year — $152/month — that did not appear in the listing's tax history.
Multiplied across the 30-year amortization period, that's $54,000 of tax that wasn't in the seller's number.
Homestead exemption and how to claim it
Most states with property tax offer a homestead exemption — a reduction in assessed value (or sometimes a tax credit) for the property that's the owner's primary residence. In Texas, the homestead exemption removes $100,000 from the assessed value for school district tax purposes, plus typical local exemptions of $5,000–25,000 from county and city.
Claiming the exemption is a one-time application filed with the county appraisal district, generally between January 1 and April 30 after you take ownership. It is your responsibility — the county doesn't auto-apply it. Homeowners who forget can lose 1–2 years of exemption before catching it.
Other tax-related costs
MUD and PID assessments
Municipal Utility Districts (MUDs) and Public Improvement Districts (PIDs) finance infrastructure for newer subdivisions through bond debt repaid via additional property tax assessments. Common in newer developments around DFW, Houston, and Austin. MUD assessments can add 0.3–0.7% to the effective rate, with the schedule typically declining over 20–30 years as the underlying bonds amortize.
Properties in MUDs are required to disclose this at sale (Texas Property Code §49.452). Buyers should read the MUD disclosure and verify the assessment is included in the projected tax line, not just the base property tax.
Special assessments
Distinct from MUDs/PIDs, these are one-time charges levied by a city or HOA for specific infrastructure (a road project, a new sidewalk, a sewer extension). Less common than MUDs but worth checking the title commitment for.
Transfer tax / recording fees
One-time at closing. In Texas there's no state transfer tax (a structural advantage compared to states like New York or Pennsylvania). Recording fees run a few hundred dollars and are part of the standard closing-cost line.
How to project your real tax bill
- Look up the local effective tax rate. County appraisal district websites publish the combined rate for each jurisdiction.
- Multiply by the purchase price for a base case.
- Add MUD/PID assessments if the property is in one (check the disclosure or call the appraisal district).
- Subtract the homestead exemption savings (if you'll occupy as primary residence).
- Use that figure in the calculator — not the listing's tax history.
The True Monthly Cost calculator takes effective tax rate as a direct input so you can run this projection in seconds rather than discovering it three months after closing.
Protesting your assessed value
If the appraisal district sets your assessed value above what you paid (this happens, usually in fast-rising markets), you can protest. The protest window in Texas is typically May 15 to mid-June. The protest evidence is straightforward: comparable sales in the neighborhood, the closing disclosure showing your purchase price, and any condition issues that affect value.
A successful protest reducing assessed value by $25,000 saves about $525/year at a 2.1% rate. The protest itself is free; many homeowners do it themselves; tax-protest services charge a percentage of the savings if you'd rather not.