Plan for supplemental property taxes by collecting the right documents before closing and checking who will receive and pay each bill. Your purchase price alone does not establish the amount to set aside.
Correction — September 7, 2026: This guide previously used the wrong period in an October example and gave broad assumptions about payment timing and budgeting. It now focuses on a practical checklist. The corrected calculation is in our supplemental-tax explanation.
Before closing: build a parcel-specific file
Ask for the parcel number, current annual tax bill, assessed-value information and your anticipated recording date. For new construction, also ask what improvements have been assessed and whether further notices are expected.
Use a worksheet to separate what you know from what still needs confirmation:
| Question | Where to confirm it | Record in your file |
|---|---|---|
| What assessed values apply? | County assessor | Values, effective dates and notice references |
| Which billing period applies? | County supplemental notice or calculation | Start/end period and factor |
| What charges are included? | County tax bill or tax collector | Applicable rate and separate parcel charges |
| Will an impound account pay this bill? | Your lender | Written answer and any action required |
| Has escrow collected anything for it? | Your escrow officer | The relevant settlement-statement entry |
After closing: check every county notice
The Los Angeles County property-tax portal explains that supplemental bills are sent to the property owner and generally are not paid from an impound account. It also explains that the timing of the reassessment can produce more than one bill. County supplemental-tax FAQ.
When a notice arrives, match its parcel number, event date and assessed values to your records. Note its installment deadlines and keep proof of payment. If something does not match, contact the agency named on the notice with the document in hand.
Use a calculation, not a purchase-price rule of thumb
For a worked example, use our corrected calculation guide alongside the BOE's official explanation. Ask the county or your adviser to confirm which assumptions apply to your parcel before treating an estimate as your budget.
For a home still under construction, request a written explanation of which values and charges the builder's tax estimate includes. Keep it with the contract and later county notices so you can identify differences.
Frequently asked questions
How much should I save?
Start with a parcel-specific estimate using the assessed-value difference, applicable rate and billing period. Until those inputs are confirmed, treat the estimate as unresolved rather than substituting a fixed share of the purchase price.
When will the bill arrive?
Processing varies. Ask the county about your notice and continue checking your mail; this guide does not promise a number of weeks after closing.
Is this page a second version of the calculation article?
This page is a document and budgeting checklist. The companion explanation covers the calculation and corrected example.
Bring these questions to your next buyer meeting, or contact Rose District for help organizing them. Official guidance linked here was checked September 7, 2026.