Pulling a building permit does not reassess your Brentwood property taxes. Completing assessable new construction does, and only the new portion gets reassessed. The permit is how the Assessor learns the work happened. It is not the trigger. Under Proposition 13, the rest of your property keeps its existing base year value.
Across 460+ East Bay closings over twenty years, this is the fear that stops people improving homes they intend to keep, and it is usually based on a misunderstanding of one word.
What actually triggers a reassessment?
Two things: a change in ownership, and completion of new construction.
Contra Costa County describes the second as any substantial addition to real property, giving adding a new room, pool or garage as examples, or any substantial alteration which restores a building, room or other improvement to the equivalent of new. California implemented supplemental assessments effective July 1, 1983, which is why the bill arrives separately and often months later.
The statute behind it is Revenue and Taxation Code section 70, which defines newly constructed property as any addition to land or improvements including fixtures since the last lien date, and any alteration since the last lien date that constitutes a major rehabilitation or converts the property to a different use.
Note what is not in there. The words are addition, major rehabilitation and different use. Not permit.
Where is the line between maintenance and new construction?
The State Board of Equalization draws it in Property Tax Rule 463, and it is more specific than most people expect.
Assessable as an addition, per Rule 463(b)(1): adding land fill, retaining walls, curbs, gutters or sewers to land; constructing a new building or swimming pool; or changing an existing improvement so as to add horizontally or vertically to its square footage, or to incorporate an additional fixture.
Assessable as an alteration, per Rule 463(b)(3): any physical alteration of an improvement which converts it, or a portion of it, to the substantial equivalent of a new structure, or which changes the way the altered portion is used.
Not assessable, per Rule 463(b)(4): construction or reconstruction performed for the purpose of normal maintenance and repair. The rule names examples, and two of them matter to almost every homeowner: interior or exterior painting and replacement of roof coverings.
Fixtures get their own treatment under Rule 463(b)(5): substantial rehabilitation or modernization converting a fixture to the substantial equivalent of a new one, or substituting a new fixture, is assessable.
So does a kitchen or bathroom remodel reassess?
I am not going to answer that, and you should be suspicious of anyone who does in a blog post.
Rule 463 gives the legal test, which is whether the alteration converts the portion to the substantial equivalent of new. Applying that test to a specific project is a fact-specific determination made by the County Assessor, not by an agent, a contractor or a website. The rule expressly names painting and roof coverings as maintenance. It does not name kitchens or bathrooms either way.
If the answer matters to your budget, call the Contra Costa County Assessor at (925) 313-7400 and describe the actual scope before you start. That is a free phone call about a number that follows you for as long as you own the house.
One related point worth knowing: under Revenue and Taxation Code section 70(c), where property is damaged or destroyed by misfortune or calamity, reconstruction that restores it to its condition before the damage is not new construction. Only the portion exceeding substantially equivalent reconstruction is.
What about an ADU?
An accessory dwelling unit is new square footage, which puts it squarely in Rule 463(b)(1) territory as an addition.
The important part is what does not happen. Adding an ADU does not reassess the whole property. The existing home keeps its Proposition 13 base year value and the new unit is added at its market value. If you are weighing an ADU in Brentwood, that distinction is the one to build your numbers on.
If you're buying or selling in Brentwood
If you're buying: the seller's current tax bill is not your future tax bill. A change in ownership reassesses the property, and Contra Costa reassesses as of the first day of the month following the ownership change, with a supplemental bill to follow. Budget from the purchase price, not from the seller's assessment.
If you're selling: if you added square footage or a pool, expect buyers to ask what it did to the assessment, and have the answer. If you replaced the roof and repainted, you can say plainly that Rule 463 treats both as normal maintenance.
Frequently asked questions about reassessment in Brentwood
Does pulling a permit reassess my property taxes?
No. Reassessment is triggered by a change in ownership or by completion of assessable new construction, not by the permit itself. The permit is how the County Assessor learns that work was done.
Does replacing a roof trigger reassessment?
State Board of Equalization Property Tax Rule 463(b)(4) expressly names replacement of roof coverings, and interior or exterior painting, as construction performed for normal maintenance and repair, which is not assessable as new construction.
Does adding a room or a pool trigger reassessment?
Rule 463(b)(1) treats constructing a new building or swimming pool, and changing an existing improvement so as to add horizontally or vertically to its square footage, as an assessable addition. Contra Costa County gives adding a new room, pool or garage as examples of new construction.
Will an ADU reassess my whole property?
No. New square footage is assessable as an addition, but only the newly constructed portion is added at its market value. The existing home retains its Proposition 13 base year value.
Does a kitchen remodel reassess my Brentwood home?
That is a fact-specific determination by the County Assessor. Rule 463(b)(3) makes an alteration assessable where it converts a portion of the improvement to the substantial equivalent of a new structure, and the rule does not name kitchen or bathroom remodels either way. Call the Contra Costa County Assessor at (925) 313-7400 with the actual scope before you start.
The Bottom Line on Brentwood Remodels and Reassessment
Additions and conversions to the substantial equivalent of new are assessable. Normal maintenance and repair is not, and the rule names painting and roof replacement specifically.
Only the new portion gets reassessed, never the whole house. If your project sits near the line, one phone call to the Assessor settles it before you spend the money.
Weighing a project against a move?
Send me the address and the plan and I will tell you what it is likely to be worth in this market before you commit.
See homes for sale in Brentwood
Thinking of selling instead? Start with a valuation, or call or text 925-250-9611.
Sources
Contra Costa County, Supplemental Property Taxes for reassessment on a change in ownership as of the first day of the month following the change, for completion of new construction described as any substantial addition or substantial alteration restoring an improvement to the equivalent of new, and for supplemental assessments taking effect July 1, 1983.
California Revenue and Taxation Code section 70 for the definition of newly constructed property, including additions since the last lien date and alterations constituting major rehabilitation or converting the property to a different use, and section 70(c) for the treatment of reconstruction after misfortune or calamity.
California State Board of Equalization, Property Tax Rule 463 for subdivision (b)(1) on assessable additions, (b)(3) on alterations converting an improvement to the substantial equivalent of a new structure, (b)(4) on normal maintenance and repair including interior and exterior painting and replacement of roof coverings, and (b)(5) on fixtures.
Assessment practice and rules change, and every project is fact-specific. Confirm the treatment of a specific project with the Contra Costa County Assessor at (925) 313-7400 and with your own tax advisor.
Jaz Chand, Broker Associate | Homes With Accent
The Jaz Team at Merrill Signature Properties | DRE #01751823
Phone/Text: 925-250-9611 | Jaz@HomesWithAccent.com
General information only, not tax or legal advice. Reassessment determinations are made by the County Assessor on the specific facts of each project. Consult the Assessor and your own tax advisor.