You took a 30-year fixed mortgage specifically so the payment would never change. Then a letter arrives saying it's going up by $90 a month. Nothing is wrong, and your rate hasn't moved — this is your escrow account being rebalanced.
Escrow is one of the least explained parts of a mortgage, and it causes more confused phone calls than almost anything else. Here's how it actually works.
What escrow is
An escrow account (your servicer may call it an impound account) is a holding account your lender maintains on your behalf to pay two bills: property taxes and homeowner's insurance. Sometimes mortgage insurance and flood insurance too.
Rather than you receiving a large tax bill once or twice a year, the lender divides the annual cost by twelve, adds it to your monthly mortgage payment, holds the money, and pays the bills when they come due.
So your monthly payment has two quite different halves. The principal and interest portion is fixed by your loan contract and genuinely does not change on a fixed-rate mortgage. The escrow portion is an estimate of third-party bills that nobody controls — and it changes whenever those bills change.
Why lenders insist on it
Unpaid property taxes create a tax lien that takes priority over the mortgage. If you stopped paying taxes and the property were seized, the tax authority would be paid before the lender. Similarly, an uninsured home that burns down destroys the lender's collateral.
Escrow removes both risks by taking the payments out of your hands. It's protection for the lender that happens to be convenient for most borrowers — the bills genuinely do get paid on time.
Whether escrow is required depends on your loan and equity. Government-backed loans generally require it. On a conventional loan, lenders typically require escrow below a certain equity threshold and may waive it above — sometimes for a small fee or a slightly higher rate.
The annual escrow analysis
Once a year your servicer performs an escrow analysis. It reviews what actually got paid out over the past year, projects what the coming year will cost, and recalculates your monthly escrow contribution. This is the letter that changes your payment.
Three things drive the change:
- Your property tax bill moved. Reassessment, a new millage rate, or the expiry of an exemption. This is usually the biggest factor.
- Your insurance premium moved. Premiums have risen sharply in several markets, and a renewal increase flows directly into your escrow.
- Last year's estimate was wrong. If the actual bills exceeded the projection, the account ran short and has to be topped back up.
Shortages, surpluses, and the cushion
A shortage means the account holds less than it should. This is the painful case, because your payment goes up twice over: the ongoing monthly contribution rises to cover the higher bills, and you also have to repay the gap. Servicers typically offer to spread the repayment over twelve months, or you can pay it as a lump sum and keep the monthly increase smaller.
A surplus means you overpaid. Above a threshold amount, the servicer generally refunds it; below, it's usually applied against the next year's contributions.
Lenders are also permitted to hold a cushion — a limited buffer, capped by federal rule at roughly two months of escrow payments — so that a modest increase doesn't immediately create a shortage. This is why your escrow balance always looks higher than strictly necessary.
The first-year trap
New-build buyers get caught by this constantly. In the first year, the property may still be assessed as vacant land rather than as a finished home. The lender sets up escrow based on that low tax bill, and everything looks affordable.
Then the property is reassessed with the house on it, the tax bill multiplies, and the first escrow analysis delivers a large shortage plus a much larger ongoing payment. The same thing happens when a previous owner's exemption — a homestead exemption, or a senior or veteran reduction — doesn't transfer to you.
If you're buying new construction, or from an owner who held an exemption, ask what the tax bill will be once your assessment applies. Budget for that figure, not the one in the listing.
Should you waive escrow if you can?
If your lender allows it, waiving escrow means you pay the tax and insurance bills yourself. The argument for it is control: you hold the money, potentially in an interest-bearing account, until the bills are due. Some states require interest on escrow balances; many don't.
The argument against is discipline. You must reliably set aside a meaningful sum every month for bills that arrive infrequently, and the consequence of getting it wrong is a tax lien. Most borrowers are better served by escrow, and the ones who genuinely benefit tend to be those who would have saved the money anyway.
What to actually do when the letter arrives
- Read the analysis, don't just note the new payment. It itemises what was paid and what's projected. The change is usually explained on the page.
- Check the split. Confirm the increase is escrow and not something else. Principal and interest should be unchanged on a fixed-rate loan.
- Verify the tax figure. If your assessment jumped, you may be able to appeal it with your county assessor. A successful appeal lowers the bill and, eventually, the escrow.
- Shop your insurance. This is the component you can most easily change. A cheaper policy reduces escrow directly.
- Consider paying a shortage as a lump sum if you have the cash, to keep the ongoing monthly increase as small as possible.
The bottom line
Escrow is a holding account for your property taxes and insurance, collected monthly alongside your mortgage. Your principal and interest are genuinely fixed; your escrow isn't, because it tracks bills set by your county and your insurer.
When the payment changes, it's almost always the tax assessment or the insurance renewal. Both are worth checking rather than accepting — and if you're buying new construction, assume the first year's tax figure is not the real one.
Our property tax guide covers assessments and exemptions in more depth, and the calculators let you enter your own tax and insurance figures to see the full monthly cost rather than just principal and interest.