The principal-and-interest number in a mortgage calculator is not your full monthly housing payment. Property taxes and homeowners insurance can add anywhere from a couple hundred dollars a month to well over a thousand, and the difference depends heavily on where and what you're buying. If you budget from principal and interest alone, you can be approved for a house whose real monthly payment does not fit your life.
The average U.S. household pays around $2,459 a year in property taxes (Bankrate/ATTOM, 2024 data), and the average annual homeowners insurance premium is projected at $3,057 in 2026, up 4% from 2025's $2,948 (Insurify, as of March 18, 2026). Together, that is roughly $450 a month nationally—but that average is basically fiction for any particular address. Your number could be half that or triple it, before mortgage insurance or HOA dues enter the picture.
Lenders often bundle taxes and insurance into an escrow account, so they appear in the same monthly bill as principal and interest. That is convenient, but it also makes it easy to mistake “the mortgage” for the full cost of the house. Affordability starts with the complete payment, not the attractive number at the top of a listing-site calculator.
Property taxes vary by a factor of 4x or more depending on where you buy
Property tax isn't a federal number — it's set locally, funds schools and municipal services, and varies wildly by state and even by county within a state. Using effective tax rate (tax paid as a percentage of home value), the gap between the highest- and lowest-tax states is enormous:
| State (high end) | Effective rate | State (low end) | Effective rate |
|---|---|---|---|
| Illinois | 1.84% | Delaware | 0.40% |
| New Jersey | 1.52% | Alabama | 0.41% |
| Connecticut | 1.41% | Arizona | 0.41% |
| Texas | 1.38% | Hawaii | 0.42% |
| Ohio | 1.35% | Idaho | 0.42% |
Source: Bankrate, using ATTOM Data Solutions, 2024 tax-year data. New Hampshire (1.24%), New York (0.82%), and Louisiana (0.77%) land in between. A separate Tax Foundation analysis (2024, five-year county estimate) pegs New Jersey even higher, around 2.49% — the exact ranking shifts a bit by methodology, but the pattern holds: Illinois owners pay roughly 4x what Alabama or Delaware owners pay on an identically priced house.
Do the math in dollars: on a $400,000 home, Illinois' 1.84% rate runs about $613/month in property tax alone. The same house in Delaware at 0.40% runs about $133/month. Nearly a $500/month gap on an identical purchase price, before insurance even enters the picture — worth checking before you fall in love with a listing, not after.
Your tax bill can jump the moment you buy — and it's not the seller's fault
Here's the part that blindsides a lot of first-time buyers: the property tax number you see on a listing (or the seller's last tax bill) is often not what you'll actually owe. Most counties reassess a property when it changes hands, and the new assessed value frequently becomes something close to the purchase price — not whatever the previous owner's assessment happened to be, which may have been locked in (or under-assessed) for years. If you buy a house that last sold in 2015 for $220,000 and you're paying $420,000 today, your county may reassess it near your purchase price, roughly doubling the tax bill the prior owner was used to.
This hits new-construction buyers especially hard, since a newly built home often has no prior tax history at all — lenders estimate the tax escrow using rough formulas (a percentage of sale price, for example) until the county finishes its first real assessment, which can land meaningfully higher (NBC/CNBC, 2026). The fix isn't avoidable, but it's plannable: ask your agent or the county assessor's office what the property would likely be reassessed at post-sale, not just what the current bill says, before you finalize your budget.
How taxes get handled at closing
Property taxes are usually paid in arrears or in advance depending on the state, and whichever way it works locally, the seller and buyer prorate the tax bill for the days each of them owned the home during the tax period. If the seller already paid the full year's tax bill and you're closing in July, you'll typically credit them for the months you'll own the home; if taxes are paid in arrears, the seller instead credits you at closing for their share, and you pay the full bill when it's due (Nolo). Either way, this proration is a one-time closing-day adjustment — it's not what sets your ongoing monthly payment. That's escrow's job.
Escrow: how principal, interest, taxes, and insurance become one payment
Almost every lender requires an escrow (or "impound") account for a loan with less than 20% down, and plenty of lenders set one up regardless. Here's the mechanics: the lender estimates your annual property tax bill and annual insurance premium, adds them together, and divides by 12. That amount gets tacked onto your principal-and-interest payment every month. The lender holds the money and pays your county and your insurer directly when the bills come due, so you're never staring down a $7,000 lump-sum tax bill in one shot (Wells Fargo).
The catch: those are estimates, and they're wrong more often than not, in either direction. Once a year, your servicer runs an escrow analysis comparing what they collected to what they actually paid out.
- Escrow shortage: taxes or insurance came in higher than estimated (very common right now, given how fast insurance premiums are climbing — more below). You'll typically get billed the shortfall, either as a lump sum, spread over the next 12 months of payments, or some combination of both (Experian). This is the single most common reason a mortgage payment goes up even on a fixed-rate loan.
- Escrow surplus: costs came in lower than estimated. Most lenders will either cut you a refund check (if the surplus is over a small threshold, often around $50) or just lower next year's monthly escrow contribution.
Either way, your servicer sends a notice explaining the new monthly payment — read it. "Your payment is going up $180/month" with no context is exactly the kind of letter people either panic over or ignore, and neither reaction helps you.
Homeowners insurance: the piece that's changing fastest
If property tax is the stable-but-locally-variable cost, insurance is the volatile one. Nationally, average homeowners insurance premiums rose roughly 11% in 2023, 11.4% in 2024, and 12% in 2025, with a projected 4% increase in 2026 to about $3,057/year (Insurify, March 2026; LendingTree, State of Home Insurance 2026). Cumulatively, that's a real jump in a handful of years — and it's not evenly spread. Climate-risk-exposed states are getting hit hardest: severe convective storms (hail, tornadoes, wind) have pushed cumulative increases since 2023 to roughly +64% in Minnesota, +55% in Colorado, and +54% in Iowa, and California is projected to see the fastest single-year jump in 2026 at nearly +16% as insurers reprice wildfire risk (Insurify).
What actually drives your specific premium:
- Location and climate risk — hurricane, wildfire, hail, and flood exposure are the single biggest factor, and it's why identical homes in different states (or even different counties) can carry wildly different premiums.
- Home age and construction — older roofs, outdated electrical/plumbing, and non-fire-resistant materials all raise premiums; a newer build or recent roof replacement can meaningfully lower one.
- Coverage level — insuring to full rebuild cost (not just purchase price) costs more up front but protects you from being underinsured after a major loss.
- Deductible — a higher deductible lowers your premium but raises your out-of-pocket cost when you actually file a claim; this is a real trade-off worth thinking through, not just a box to check quickly during closing.
Worth flagging: in some high-risk markets (parts of Florida, California, and Louisiana especially), insurers have pulled back or dropped coverage entirely, pushing homeowners into state-run "insurer of last resort" plans that cost more and cover less. If you're buying somewhere with real climate exposure, get an actual insurance quote before you're locked into a purchase contract, not after, when you have no leverage to renegotiate.
The bottom line
Property tax and insurance together can easily be $300–$1,500+ a month depending on geography. That means “how much house can I afford?” is genuinely a different question in Illinois than in Delaware, or in coastal Florida than in inland Ohio—even at the same sale price and mortgage rate.
Before you get attached to a specific home, build your budget from the complete monthly payment: principal, interest, realistic post-sale property taxes, an actual insurance quote, mortgage insurance if applicable, and HOA dues if there are any. Ask your agent or lender for a post-sale tax estimate rather than relying on the seller's old bill. Taxes and insurance can both move after closing, so leave room for the payment to change even when the mortgage itself is fixed-rate.
Sources
- Bankrate — Property Tax Rates by State (ATTOM Data Solutions, 2024)
- Tax Foundation — Property Taxes by State and County (2024 five-year estimate)
- NBC/CNBC — Buyers of newly built homes can face a property tax surprise (2026)
- Nolo — Who Pays Property Taxes at Closing
- Wells Fargo — What Is an Escrow Account and How Does It Work
- Experian — What Is an Escrow Shortage
- Insurify — 2026 Home Insurance Price Projections (March 18, 2026)
- LendingTree — State of Home Insurance 2026
Note: the 2023–2025 year-over-year insurance increase figures (11%, 11.4%, 12%) come from Insurify's and LendingTree's 2026 trend reporting; exact figures vary slightly by provider (Insurify vs. LendingTree vs. Insurance Information Institute) depending on methodology, so treat the direction and rough magnitude as solid, not the last decimal point.