California rent increase laws: notice, caps, and what a valid notice must include

California rent increase laws set both a cap on the amount, under AB 1482, and a strict procedural requirement for how the increase is communicated — and the second part is where increases that are otherwise perfectly legal end up getting successfully challenged.

The cap

For most units covered by AB 1482, the maximum annual increase is 5% plus the regional Consumer Price Index, capped at 10% total, whichever figure is lower. That percentage is recalculated every year using CPI data specific to the property's metro area, so a landlord operating in multiple California cities cannot apply the same percentage across all of them.

Notice period by size of increase

An increase of 10% or less requires 30 days' written notice before it takes effect. An increase above 10% — which is only possible on an exempt property, since covered units cannot legally exceed 10% — requires 90 days.

What a valid notice must actually contain

A compliant rent increase notice needs the new rent amount, the dollar amount of the increase, the effective date, the tenant's name, the property address, and the landlord's signature. A notice missing any of these — a common failure is omitting the exact effective date, or sending an unsigned notice — can be challenged as procedurally invalid even if the percentage itself was fully within the legal cap.

Exemptions worth double-checking

Single-family homes and condos not owned by a corporation or REIT, units in buildings under 15 years old, owner-occupied properties, student housing, and most mobile home tenancies fall outside AB 1482's cap. An exemption generally requires written disclosure to the tenant to actually apply — a property that qualifies for the exemption but never gave that written notice can still be held to the capped rules.

Local rules can be stricter than the state cap

San Francisco, Los Angeles, and other cities with rent control ordinances predating September 2019 apply their own limits on top of the state law, and those local caps can be tighter than AB 1482's formula. Checking the specific city ordinance matters as much as checking the state law for any property inside one of these jurisdictions.

Getting the notice period right depends on knowing the exact increase percentage relative to 10%, and getting the notice itself right depends on including every required field — two separate failure points that are easy to catch with a template built for this, and easy to miss recreating from scratch each time. Rent collection tools that generate increase notices from the lease record already on file remove both risks by construction.

Calculating the maximum increase

For a covered unit, the maximum over any twelve months is the lowest rent charged in that period multiplied by one plus the cap, where the cap is 5% plus the regional CPI change, never more than 10%. The California rent increase calculator does the arithmetic and shows the notice period that applies; which units are covered, and which cities have stricter rules, is explained in California rent control.