The 30-year fixed mortgage was supposed to be predictable. Two costs quietly broke that promise

A new survey shows 40% of homeowners said they’ve considered moving because their property taxes have gotten so high.

Potential homebuyers tend to agonize over two things: mortgage rates and home prices. But that’s not where the burden of homeownership ends. It’s really just the beginning.

Buyers will lock in a rate, sign at closing, and assume the hard part of buying a house is over, but many things can go wrong, and there are many hidden homeownership costs that not everyone stops to consider. 

For example, a recent survey of 2,500 U.S. homeowners from Ownwell, a property tax appeal service, found 76% say their property taxes in recent years have run higher than they budgeted for—up 10 percentage points from just a year earlier. Nearly two-thirds said they were surprised or shocked by their most recent tax bill, and 9 in 10 said they’re concerned about the long-term financial hit of rising property taxes. And even more startling is 40% said they had considered moving specifically because of them.

“Taxes have quietly joined insurance as one of the biggest affordability shocks after closing, especially in states with high property taxes like New York, Massachusetts, and Texas,” Ownwell CEO Colton Pace told Fortune. 

These new stats point to an affordability problem the usual housing conversation misses. While it’s more accessible (albeit sometimes painful) to monitor mortgage rates and home prices, recurring expenses like taxes, insurance, maintenance, and other line items that nobody mentions at the closing table are quietly reshaping what it actually costs to keep a home.

“The fixed-rate mortgage was supposed to be the one predictable cost in your life,” Pace said. “Rising insurance and property taxes have quietly broken that promise.”

The unpredictability of homeownership

A 30-year fixed mortgage is the rare household bill that doesn’t change month-over-month or year-over-year—but the taxes and insurance bundled into the monthly payment do. Every year, taxes and insurance can change a county-by-county schedule or at renewal, respectively. 

“Homeowners aren’t tracking two separate bills,” Pace said. “They’re waiting for an escrow letter or a county notice of value to tell them their payment just changed.”

The math behind those notices has gotten harder to predict. The average sales price of new homes rose roughly 23% on average over the past five years, according to Federal Reserve data, and tax assessments followed. Property taxes reset annually and hinge on factors—local housing markets, county and city budgets, and the tax rates that flow from them—that even economists struggle to forecast, Pace said. That means homeowners can get hit with an unexpected amount.

What agents tell buyers they’re missing

Real estate agents see the same blind spots in their clients.

“Buyers seem to be more focused on the mortgage rate and the price of the home, and forget about the other expenses that could be more a month than their mortgage,” Kori Sassower, principal agent of The Kori Sassower Team at Compass, told Fortune. Sassower is dually licensed in New York and Connecticut. 

Taxes are the biggest of those variables, she said, and they can vary greatly from one town, village, or city to the next. But the cost that catches buyers off guard most is maintenance, which can include seasonal HVAC servicing, pest control, tree trimming, power washing, gutter cleaning, and stone repointing. Property taxes, in her experience, are “the number 1 driver that makes people sell their homes.”

For condo buyers, monthly association fees are another expense that can increase over time, Miltiadis Kastanis, a Miami-based real estate agent with Compass, told Fortune.

“Good advisors prepare buyers for these costs upfront, but there’s always a learning curve once someone becomes a homeowner because the true cost of ownership extends well beyond the monthly mortgage payment,” Kastanis said.

The hidden costs of homeownership

The hidden costs of owning a single-family home—property taxes, insurance, utilities, internet, and maintenance—now cost more than $21,000 per year nationally, according to Bankrate’s 2025 study. Maintenance alone accounts for $8,808 of that, the single largest piece. 

The most common regret among homeowners who had one was that upkeep and other hidden costs ran more expensive than they’d expected, according to the Bankrate survey. 

And while Michelle Griffith, a New York City-based real estate agent with Douglas Elliman, said NYC buyers are generally more aware of property taxes and other monthly costs, what tends to surprise them more are less obvious expenses like assessments, maintenance fees, furnishings, and the costs of maintaining a larger residence.

“Buyers relocating from rentals also underestimate how quickly everyday ownership expenses add up, particularly in luxury buildings where the expectation is to maintain a certain standard of living,” she told Fortune. 

Insurance comes with its own separate shock. The average annual home insurance premium jumped 12% in 2025 and is on track to rise another 4%, to about $3,057, by the end of 2026, according to Insurify. Premiums have climbed 46% since 2021—roughly three times the pace of inflation. The pain is concentrated in disaster-exposed states: Florida’s typical premium is approaching $8,500, and California is expected to see the steepest increases in 2026 following the Los Angeles wildfires.

So for a generation that already waited longer and saved harder to buy a home, the down payment and the rate get a buyer through the door. Everything after closing determines whether they can afford to stay.

“Recurring expenses may not make a home unaffordable on paper, but they can meaningfully impact a homeowner’s monthly budget and lifestyle,” Kastanis said.

This story was originally featured on Fortune.com