How to watch for a supplemental property tax bill
In California, a sale triggers a new assessment, and you may get one or two supplemental property tax bills for the difference. These bills aren't mailed to your lender, and your impound account won't pay them. Watch your county tax collector's website after closing and pay any bill yourself by its due date.
What a supplemental property tax bill is
California property tax law requires the assessor to revalue a home when ownership changes. Your regular tax bill for the year was based on the last owner's value, so a supplemental bill collects the difference for the part of the fiscal year you own the home. It comes on top of your annual bill and doesn't replace it.
The awkward part is who it goes to. State law requires buyers to get a notice saying these bills aren't mailed to the lender, and that if you use an impound account, your lender won't pay them. Paying the tax collector is your job, even if you've never paid a tax bill directly.
When a supplemental tax bill arrives
Start looking a few weeks after closing, then check again every month or so until a bill appears. The assessor has to process the sale first, so the timing varies by county. Orange County says a new buyer won't get a new annual secured bill until the following September, so don't read a quiet mailbox as good news. Update your mailing address with the assessor if the bill might go to the old address.
How to estimate a supplemental assessment
You can estimate the bill with simple math: the change in value, times your tax rate, times the share of the fiscal year left. California's fiscal year ends June 30. These are sample figures, so use your own tax rate from a county bill.
| Line | Sample |
|---|---|
| Prior owner's taxable value | $300,000 |
| New value after sale | $500,000 |
| Increase | $200,000 |
| Tax on the increase for a full year, at a sample 1.1% | $2,200 |
| Share of fiscal year left (closing near January 1) | Half |
| Sample supplemental amount | About $1,100 |
The month matters. Orange County says transfers between January 1 and May 31 trigger two supplemental assessments. If the new value is lower, you'd get a refund instead, which can take about 2 to 3 months.
How to handle a supplemental property tax bill
- Find your parcel number
It's on your closing papers or the assessor's site. You'll use it to look up every bill.
- Look up the county tax site
Search your parcel a few weeks after closing and set a monthly reminder until a supplemental bill shows up.
- Read the notice of assessment
Compare the new value with what you paid. Note how many bills are coming and the dates.
- Confirm who is paying
Ask your servicer if it will pay from escrow. If it won't, plan to pay directly, and get any exception in writing.
- Pay by the due date
Pay the tax collector directly and save the receipt, which also supports your tax records.
- Apply for your exemption
Send in the homeowner's exemption application if the home is your main residence.
- Tell your servicer the new value
Ask it to use the new assessment in your next escrow analysis, so you aren't surprised by a shortage.
California supplemental tax bill rules and other states
The rules on this page are California's. Other states handle a sale their own way. You may see a separate bill, a jump on your next regular bill, or an adjusted figure in your escrow. Ask your county assessor or tax collector how a sale is treated where you bought. Even within California, due dates, online tools and contact details come from your county.
Does escrow pay supplemental taxes? What to watch for
- Assuming escrow handled it. Your lender doesn't get the bill. Orange County suggests asking your lender if the impound account has enough to cover it, but plan on paying directly.
- A short impound balance. Impounds may be based on the old value, so your monthly payment can rise after your first escrow review.
- A missed mailing. The bill is still your responsibility, and county relief from late penalties may be limited. Ask your tax collector right away if you've missed a date.
- Mixing up the bills. A supplemental bill and an annual bill have separate due dates, so pay each one.
- Exemptions. A homeowner's exemption doesn't carry over from your old house. You have to apply for your new one.
- A value you disagree with. You can appeal, but the window is short. Check your county's deadline as soon as the notice arrives.
Supplemental tax bill questions
Why did I get a supplemental tax bill after buying a house?
California revalues a home when it changes hands. The bill collects the difference between the old and new values for the rest of the fiscal year.
Does my lender pay the supplemental tax bill?
Generally no. California's required notice says these bills aren't mailed to your lender and won't be paid through your impound account. Ask your servicer if you want to confirm.
Is a supplemental tax bill a one-time charge?
Yes, for that change in ownership, though you may get one or two bills. After that, the new value shows up on your regular annual bill.
Sources: california.public.law, ocassessor.gov
General guidance for U.S. homes, not professional advice. For gas, electrical and structural work, call a licensed pro.