AB 1482 90-day notice rule Any rent increase of 10% or more — or any cumulative increase over 12 months that crosses 10% — needs 90 days written notice, not 30.

The rule, in one paragraph

California month-to-month tenants receive 30 days written notice for any rent increase that is less than 10% of the lowest rent charged in the previous 12 months. They receive 90 days written notice for any single increase of 10% or more, or for any increase whose cumulative total (when combined with other increases in the prior 12 months) exceeds 10%. The 90-day floor exists precisely to give tenants time to absorb a large jump or, if they can't, find new housing without the cliff a 30-day timeline creates.

Cumulative is the trap most landlords miss

The single-increase trigger is intuitive: if today's rent is $2,000 and you're moving it to $2,300, that's a 15% jump and 90 days is obviously required. The cumulative trigger is where landlords routinely miscount. §827(b)(3) anchors the 10% threshold on the lowest rent charged during the 12 months before the new effective date — not the current rent the tenant is paying today.

A worked example: a $2,000 unit gets a 5% increase to $2,100 effective March 1, 2026. Eight months later you serve another notice moving rent from $2,100 to $2,250 effective November 1, 2026 — a 7.1% increase on its face. But the §827(b)(3) anchor rent is still $2,000 (the lowest in the prior 12 months), so the cumulative increase is $250 / $2,000 = 12.5%. Both notices needed 90 days. The November notice is defective if you served only 30, even though that single notice was under 10%.

The fix is to track the rolling 12-month rent floor on every unit. The RentCeiling calculator and the California notice generator both run this calculation automatically when you log a prior increase. Landlords doing this in a spreadsheet are the ones who get caught at trial.

How AB 1482's 8.8% cap interacts with §827(b)

AB 1482's 2026 cap of 8.8% statewide is comfortably under the 10% threshold that triggers §827(b)(3) — so landlords charging the maximum lawful increase will typically serve a 30-day notice. But three common patterns push past 10% cumulatively and force 90:

1. Two AB 1482 increases in 12 months. Lawful under the statute (no annual-frequency cap), but two 5-8% increases easily stack past 10% under §827(b)(3)'s cumulative trigger. The second notice needs 90 days.
2. An AB 1482 increase stacked on a banked local-ordinance increase. SF Rent Board Rules §4.12 and Berkeley BMC §13.76.110 banking can stack with a current-year increase to push past 10% cumulative. Same 90-day result.
3. A new tenancy after vacancy decontrol. If you raised rent on a vacant unit by 30% under Costa-Hawkins (Cal. Civ. Code §1954.53), that increase doesn't count under §827(b) because it's to a new tenant — but if the prior tenant moves back in or you make a roommate the new lessee within 12 months, the math gets messy fast.

How local ordinances overlay §827(b)

§827(b) is the statewide floor. Local ordinances can add stricter notice rules but cannot lower the floor. The most common overlays:

• LA RSO — LAMC §151.06.01 requires the notice include the LAHD registration number and a statement that the unit is RSO-covered, in addition to all §827(b) content. Service rules track §1162. The 30/90 split is unchanged.
• San Francisco — S.F. Admin. Code Ch. 37 §37.3 and SF Rent Board Rules §12.13 require the notice include a Rent Board notice sentence and the notice-period reference. Banked increases under §4.12 must separately disclose the banking calculation.
• Berkeley — BMC §13.76.080(F) requires a notice that distinguishes the AGA-allowed portion from any banked portion, with each portion attributed to its authorizing source.
• Oakland, Santa Monica, West Hollywood, Beverly Hills — each ordinance has its own content requirements but none drops below §827(b)'s 30/90 split.

Service method changes the effective date

Cal. Civ. Code §1013 adds 5 calendar days to the notice period when the notice is served by mail and the recipient address is within California. So a 90-day notice mailed on Monday, June 1, 2026 cannot take effect before Tuesday, September 1, 2026 (90 + 5 = 95 days out, counting from the mail date). For 30-day notices the mailing add is the same 5 days.

Personal service per Cal. Civ. Code §1162 does not get the 5-day add. But personal service requires actual delivery to the tenant or to a person of suitable age at the dwelling AND a copy mailed if the tenant is not personally served — and a landlord who mails the second copy as part of substituted service still gets the 5-day add. The safest practice for landlords is to plan as though every notice is mailed, so 95 / 35 days respectively.

What counts as written notice

Cal. Civ. Code §827(a) requires the notice "in writing", served on the tenant in the same manner as a notice terminating tenancy under §1162. In practice this means a paper document with:

• The tenant's name and the unit address.
• The current rent and the new rent in dollars.
• The dollar increase and percentage increase.
• The effective date the new rent takes effect.
• The landlord's signature and date of service.
• Method of service (personal / substituted / mail).
• For AB 1482-covered units: a statement of statutory compliance with the percentage cap.
• For locally-covered units: the local ordinance disclosures listed in the section above.

Email-only notice is not §827-compliant unless the tenant has expressly agreed in the lease to electronic service. Even then, most landlord-tenant practitioners recommend serving on paper as the backup-of-record. The free California notice generator produces a printable PDF with all required content for both AB 1482 and §827(b) compliance.

What happens if you get the notice period wrong

A defective notice is void as to the increase. The prior rent remains the lawful rent. Two practical consequences:

1. Overcharges are recoverable. Cal. Civ. Code §1947.12(h)(2) lets the tenant recover the overcharge — up to three times actual damages — plus attorney fees. Tenants who discover the defect during an unrelated dispute (lease renewal, maintenance, unlawful detainer) routinely surface it as a counterclaim.
2. Just-cause posture can break. A landlord who served a defective notice and accepted the higher rent for several months is in an awkward posture under Cal. Civ. Code §1946.2 — the receipts for the higher amount can be construed as evidence the landlord knew the unit was AB 1482-covered (defeating later attempts to claim exemption), and the prior rent floor remains the operative figure for any subsequent calculation.

How RentCeiling enforces this for you

The free California calculator takes (current rent, last-increase date, last-increase amount) and tells you the §827(b) notice period required for the new rent you're proposing. The notice generator consumes the same inputs and produces a printable PDF with §827(b) compliance baked in — the right notice period, the right effective date with mailing adjustment, and the AB 1482 statutory cap statement. The four-California-rent-caps explainer covers how the §827(b) floor interacts with the four distinct CA rent-cap regimes (AB 1482 / LA RSO / SF / Berkeley). Open rule-set at /rules/index.json.

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