Every affordability calculator on the internet will hand you a number for San Antonio, and almost every one of them will be too high. Not because the formula is wrong — because the formula assumes a property tax rate this county has never seen. Here is the version of the math that survives underwriting in Bexar County.
Using an illustrative 6.5% rate on a 30-year fixed, 5% down, and a real Bexar County escrow (about 2.2% property tax plus Texas hail-country insurance), a $65,000 household with $400 in monthly debts affords roughly $215,000; $95,000 with $600 in debts, about $310,000; $140,000 with $900 in debts, about $455,000. A national calculator will quote you $35,000–$75,000 more than that. It is not lying — it just thinks you live somewhere with 1.1% property taxes.
The rate above is for arithmetic only, not a quote — your rate depends on your credit, program and the day you lock. But the structure of the math does not change, and the structure is what most people get wrong here.
Why national calculators overshoot in Bexar County
Most calculators bake in something close to the U.S. average property tax — around 1.1% of value — and a modest insurance figure. Inside the city of San Antonio the stacked rate (Bexar County, the city, University Health, Alamo Colleges, the river authority, and your school district) lands roughly between 2.0% and 2.5% of appraised value depending on which ISD you are in. New subdivisions on the far West Side and north of Loop 1604 that carry a MUD or PID on top can run 2.7% or higher.
On a $350,000 home, the difference between 1.1% and 2.2% is about $320 a month. That $320 lives inside your mortgage payment, which means it lives inside your debt-to-income ratio, which means it directly shrinks what you can be approved for. At an illustrative 6.5%, every $100 a month of payment room is worth roughly $11,000 of purchase price once taxes and insurance are counted — so the tax gap alone moves your ceiling by about $35,000 on that house.
The part that surprises people who moved here from a state with an income tax: Texas leaving that money in your paycheck does nothing for your approval. Lenders qualify on gross income. The income tax you don’t pay is invisible to the ratio. The property tax that replaces it is fully visible, because it sits in the payment. Texas is generous to your cash flow after closing and stingy with your approval before it.
The ratio lenders actually run
There is no mystery formula. Add up your proposed full house payment — principal, interest, property taxes, homeowners insurance, mortgage insurance if you put less than 20% down, and HOA dues — plus every monthly debt on your credit report. Divide by gross monthly income. That is your debt-to-income ratio, and 43% is the standard benchmark. Conventional files with strong credit and reserves can be approved up to 50% by automated underwriting; FHA can go higher with compensating factors.
Two things that count against you that people forget: a car payment with eleven months left still counts in full on most programs, and a student loan in deferment is usually counted at a percentage of the balance even if the actual payment is $0. Two things that count for you in Military City: BAH counts as qualifying income, and non-taxable income like BAH and VA disability can typically be grossed up by about 25% for the ratio, because the lender knows you keep all of it.
Three San Antonio households, line by line
Same assumptions throughout: illustrative 6.5% rate, 30-year fixed, 5% down conventional financing with mortgage insurance at roughly 0.5% of the loan per year (an industry-typical figure for good credit), 2.2% property tax, insurance near 0.95% of value (a realistic San Antonio hail-country premium), no HOA, and a 43% ratio.
| Single earner | Two incomes | Dual professional / officer household | |
|---|---|---|---|
| Gross annual income | $65,000 | $95,000 | $140,000 |
| Gross monthly income | $5,417 | $7,917 | $11,667 |
| Max total debt at 43% | $2,329 | $3,404 | $5,017 |
| Existing monthly debts | $400 | $600 | $900 |
| Room left for the house | $1,929 | $2,804 | $4,117 |
| Purchase price that fits | ≈ $215,000 | ≈ $310,000 | ≈ $455,000 |
| Principal & interest | $1,291 | $1,861 | $2,732 |
| Property tax escrow (2.2%) | $394 | $568 | $834 |
| Insurance escrow | $170 | $245 | $360 |
| Mortgage insurance | $85 | $123 | $180 |
| What a 1.1%-tax calculator says | ≈ $250,000 | ≈ $363,000 | ≈ $532,000 |
Read the bottom two rows together. The national number is 15–17% too high in every tier, and the overshoot grows with income. A $140,000 household told it can shop at $530,000 will fall in love with a house in Stone Oak or Alamo Ranch that underwrites to “no” — and find out after the inspection money is spent.
Notice also that property tax is the second-largest line in every column — bigger than insurance and mortgage insurance combined. In most of the country that line is a rounding error. Here it is a third of the principal and interest.
If you want the income needed from the other direction: with $600 in monthly debts and the same assumptions, a $250,000 home needs roughly $80,000 of household income, $300,000 needs about $92,000, $350,000 needs about $105,000, $400,000 about $117,000, and $500,000 about $143,000. Run your own version on the affordability calculator on my site, then let me run the real one.
Where the 2.2% actually comes from
Texas quotes tax rates per $100 of value, and every taxing unit that touches your address adds its own line. For a home inside the San Antonio city limits, the stack looks approximately like this (current adopted rates, rounded — confirm your specific parcel at bcad.org, the Bexar Appraisal District):
| Taxing unit | Approximate rate |
|---|---|
| School district (Northside, North East, Judson, etc.) | ~1.0% |
| City of San Antonio | ~0.54% |
| Bexar County (incl. flood control) | ~0.28% |
| University Health (hospital district) | ~0.28% |
| Alamo Colleges | ~0.15% |
| San Antonio River Authority | ~0.02% |
| Stacked total | ~2.25% |
Three things move this number. Your school district is the largest and most variable line, which is why two homes at the same price in Alamo Heights ISD and Judson ISD carry different payments. Suburbs like Schertz and Cibolo trade the city line for their own municipal rate and a different county. And new construction with a MUD (municipal utility district) or PID adds a line most out-of-town buyers have never heard of — sometimes another 0.5% to 1% — and it shows up nowhere on the builder’s payment flyer.
Texas caps a homesteaded home's taxable value at 10% growth per year — and that cap resets to market value the day the home sells. A seller who bought in 2015 might be assessed at $250,000 on a home you are paying $380,000 for. Their tax bill was about $5,500. Yours will be about $8,360 — roughly $240 a month more than the "current taxes" line on the listing. I qualify you on the reset number, because that is the escrow you will actually pay. A lender who uses the seller's bill is not being generous; they are setting you up for a payment jump at the first escrow analysis.
The homestead exemption helps — after you close
The good news in the Texas tax code is real, it just arrives on a delay. Once you file the homestead exemption with the appraisal district, the state removes $140,000 of value from the school district portion of your bill (Texas voters raised it from $100,000 in November 2025). At a typical 1% school rate that is about $1,400 a year, or roughly $115 a month. The City of San Antonio and Bexar County each layer a percentage-based exemption on top, and the 10% appraisal cap starts protecting you from year two onward. Homeowners 65 and older or disabled get a further exemption and a frozen school tax ceiling.
Since 2022 you no longer have to wait for January 1 — you can file in the year you buy and the exemption is prorated from your closing date. File it the week you close. It is free, it takes ten minutes online, and anyone who mails you an offer to “file it for you” for a fee is charging you for a form.
What it does not do is change your approval. Lenders set up escrow on the taxes as they stand at closing and adjust at the next annual analysis, so the exemption improves your payment in year two rather than your ratio in month one. If the exemption is what makes the payment work, the payment does not work yet.
Insurance, HOAs and the other lines that eat your ratio
San Antonio sits squarely in hail country, and Texas homeowners insurance is priced like it. A realistic premium on a $300,000 home runs somewhere in the $2,500–$4,000 range depending on roof age, construction and whether your policy carries a percentage wind-and-hail deductible. Quote insurance on a specific address before you get attached to it; a fifteen-year-old composition roof can add $80 a month to the escrow and change which house you can buy.
Then the smaller lines that add up: HOA dues on most newer subdivisions inside Loop 1604 ($40–$120 a month is common), mortgage insurance until you reach 20% equity, and — the one that costs the most house — existing debt. At the numbers above, a $450 truck payment removes roughly $50,000 of purchase price. Paying off a car with a small balance before applying is often the highest-return move a buyer can make, and it is one I will tell you about before you spend money on anything else.
Buy the payment, not the approval
What I can approve you for and what you should actually spend are not the same figure, and I will say so out loud in our first conversation. The approval does not know about daycare in Stone Oak, the drive from Cibolo to Lackland, or the fact that Bexar County reappraises every single year. My advice: take the approved payment, subtract what your next tax notice could add (assume the full 10% cap kicks in), and make sure the result still lets you sleep.
The table above is arithmetic. Your number depends on your credit, your program, the school district you are shopping in, and how the taxes on that specific parcel reset. Start the two-minute pre-approval check — no SSN, no credit pull — and I will run the Bexar County version of the math with your actual figures, usually the same day.
Veterans and active-duty buyers at Fort Sam, Lackland and Randolph: your ceiling is often higher than the table suggests, because VA loans in San Antonio require no down payment and no mortgage insurance, which removes two lines from the payment entirely. And first-time buyers who are short on the cash rather than the income should look at Texas down payment assistance programs before they shrink the price — the ratio and the down payment are separate problems with separate fixes.
Common questions
How much house can I afford on $100,000 a year in San Antonio?
With about $600 a month in other debts, 5% down, and a full Bexar County tax-and-insurance escrow, roughly $330,000 at a 43% debt-to-income ratio. A strong file that underwrites at 45% stretches that to about $350,000. Fewer debts, a bigger down payment, or a lower-rate school district all push it higher.
What property tax rate should I budget for in San Antonio?
Plan on roughly 2.0% to 2.5% of the home's appraised value per year inside Bexar County, depending on the school district, and 2.7% or more in new-build subdivisions that carry a MUD or PID. Look up the exact stacked rate for the parcel at bcad.org before you write an offer — it is public and it takes two minutes.
Does Texas having no state income tax help me qualify for a bigger mortgage?
No. Lenders qualify you on gross income before any tax, so the money Texas leaves in your paycheck is invisible to the ratio. The property tax that replaces it is fully visible, because it sits inside your monthly payment. Texas helps your cash flow after closing; it does not help your approval.
How does the Texas homestead exemption change my mortgage payment?
Once it is filed and applied, the state exemption removes $140,000 of value from the school district portion of your bill — worth roughly $1,400 a year, or about $115 a month, at a typical 1% school rate — and the city and county layer their own percentage exemptions on top. Your escrow is adjusted at the next analysis, so expect the relief in year two, not at closing.
Why is my escrow payment higher than the seller's tax bill suggested?
Texas caps a homesteaded home's taxable value at 10% growth per year, and that cap dies the day the home sells. A long-time owner assessed at $250,000 on a home now worth $380,000 was paying about $5,500 a year; you will be taxed on $380,000, which is about $8,360. A careful lender qualifies you on the reset number, not the seller's old bill.
What debt-to-income ratio do lenders allow in Texas?
The same as everywhere: 43% is the standard benchmark, conventional files with strong credit and reserves can be approved up to 50% by automated underwriting, and FHA can go higher with compensating factors. The ratio is national. The reason it feels tighter in San Antonio is the tax line inside the payment, not the ratio itself.
Questions about your situation?
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