Why Your Mortgage Payment Isn't Really Fixed
A 30-year fixed mortgage has a fixed interest rate. What it doesn't have is a fixed monthly payment, and this catches a lot of homeowners off guard. The principal and interest portion never changes, but most people also pay property taxes and homeowners insurance through the same monthly bill. Those two pieces change every year, and when they do, your payment moves with them.
The mechanism behind this is the escrow account (some lenders call it an impound account). Understanding how it works will save you a panicked phone call to your servicer the first time your payment jumps $150 for no obvious reason.
How an Escrow Account Works
When your lender requires escrow, the monthly math looks like this:
| Component | Example Amount | Changes Over Time? |
|---|---|---|
| Principal + interest | $1,890 | No (on a fixed-rate loan) |
| Property tax escrow (1/12 of annual bill) | $425 | Yes, every year |
| Homeowners insurance escrow (1/12 of premium) | $140 | Yes, every year |
| Total monthly payment | $2,455 | Yes |
Each month, the tax and insurance portions go into the escrow account. When your county sends the tax bill, the servicer pays it directly from that account. You never touch the money, which is exactly the point: the lender wants certainty that taxes get paid, because an unpaid tax bill creates a lien that sits ahead of their mortgage.
The Annual Escrow Analysis
Once a year, your servicer runs an escrow analysis. They compare what they collected against what they actually paid out, then project the coming year. Two things can happen:
- Surplus: They collected more than needed. If the surplus is over $50, federal rules (RESPA) require them to refund it to you.
- Shortage: They collected less than needed, usually because your tax bill or insurance premium went up. Now you owe the difference.
With a shortage, you typically get two options: pay it as a lump sum, or spread it over the next 12 months. Here's the trap people miss. If you spread it out, your new payment includes both the shortage repayment and the higher ongoing escrow contribution. That's why a $600 annual tax increase can push your monthly payment up by $100 instead of the $50 you expected.
A Worked Example
Say your annual property tax bill goes from $5,100 to $5,940 after a reassessment (an $840 increase). Your escrow analysis lands in March:
| Item | Before | After |
|---|---|---|
| Monthly tax escrow | $425 | $495 |
| Shortage from last year (spread over 12 months) | $0 | $70 |
| Monthly payment change | +$140 |
After 12 months, the shortage is repaid and the payment drops back down by $70, assuming taxes don't rise again. They usually do rise again, which is why payments tend to ratchet upward.
The Escrow Cushion
Federal law lets servicers keep a cushion of up to two months of escrow payments as a buffer. On a $565 monthly escrow, that's $1,130 sitting in the account beyond projected needs. This is legal and nearly universal, but it means your escrow balance will always look higher than the bills coming due. Don't expect that cushion back unless you close the account or pay off the loan.
Can You Drop Escrow and Pay Taxes Yourself?
Sometimes. Most lenders will waive escrow if you have at least 20% equity, a clean payment history, and you ask. Some charge a fee (often 0.25% of the loan amount) at origination for the waiver. Whether it's worth it depends on your discipline:
- Pros: You keep the money until the bill is due, you can earn interest on it, and you can take advantage of early-payment discounts that some states offer. Florida, for example, gives a 4% discount for paying in November.
- Cons: You need to have several thousand dollars ready once or twice a year, every year, without fail. Miss a payment and you're facing penalties, interest, and eventually a tax lien.
If you're the kind of person who'd rather not think about it, escrow is honestly fine. The cushion costs you a little interest income and that's about it.
What to Remember
- Your payment changes because taxes and insurance change, not because the lender is doing anything wrong
- Read the escrow analysis statement when it arrives. It shows exactly what changed and why.
- If your payment jumped, check whether it's a one-year shortage repayment (temporary) or a higher tax bill (permanent)
- If the tax increase itself looks wrong, you may be able to appeal the assessment. See our guide on appealing a property tax assessment.
To estimate the tax portion of your payment for any location, use our property tax calculator.