AB 1482 Rent Cap Calculation: CPI + 5% Formula Explained — California Landlord Guide (2026)

Understanding AB 1482 and Civil Code §1947.12

In September 2019, California Governor Gavin Newsom signed Assembly Bill 1482 into law, establishing the state's first statewide rent control measure in nearly three decades. The statute, codified in Civil Code §1947.12, imposed a limit on annual rent increases for most residential tenancies in California. Unlike local rent control ordinances that apply only to specific cities (such as Los Angeles or Oakland), AB 1482 applies uniformly to rental properties across the entire state, with limited exemptions.

The law's core mechanism is a formula-based rent cap designed to balance landlord property rights with tenant protection: annual rent increases are limited to the lesser of 5% or the prior year's CPI-U plus 5%. This formula means your increase cannot exceed 5%, but it also cannot exceed the actual inflation rate (CPI) plus an additional 5% cushion. In low-inflation years, the CPI plus 5% calculation may result in a lower permissible increase than 5%; in high-inflation years, the 5% absolute cap applies.

As of October 2026, AB 1482 remains in effect through January 1, 2031, and will continue unless repealed or allowed to expire. The statute applies to all residential tenancies in California, including apartments, condominiums, single-family rentals (with exceptions), manufactured homes in parks, and mobile homes, as long as the property was built before February 1, 1995, or was otherwise subject to rent control before January 1, 1999.

Which Properties Does the Rent Cap Apply To?

Before calculating your allowable rent increase, you must first determine whether your property is covered by AB 1482. The statute contains several key exemptions:

Properties Subject to the Rent Cap

• Multi-unit residential properties (apartments, duplexes, triplexes, fourplexes with 5+ units)
• Single-family homes (with limited exceptions noted below)
• Condominiums not held in common interest development
• Manufactured and mobile homes in parks
• Tenancies that began before January 1, 1999, or the property was subject to rent control on January 1, 1999

Properties Exempted From the Rent Cap

• Single-family homes owned by a natural person (with narrow exceptions): If you personally own a single-family home as your primary residence or own only one single-family home as a rental, the rent cap does not apply. This exemption is lost if you own more than one single-family home, if a corporation or LLC owns the property, or if you have been subject to a local rent control ordinance.
• Newly constructed units (first 15 years after initial occupancy): Properties built on or after February 1, 1995, are exempt from AB 1482 for the first 15 years after a tenant first occupies a unit. After 15 years, the rent cap applies.
• Luxury units and student housing: Properties designated as luxury (over $3,000 initial rent in 2019, adjusted annually) or student housing operated by educational institutions may qualify for exemptions under specific conditions.
• Tenancies with operating cost pass-through clauses: Properties with valid lease language allowing pass-through of operating cost increases are exempt, provided the pass-through language was in place before January 1, 2019.

If you are uncertain whether your property qualifies for an exemption, document your reasoning in writing. Tenant disputes over exemptions have led to litigation; California courts have narrowly construed exemptions in favor of tenant protection. When in doubt, apply the rent cap.

How to Calculate the CPI Plus 5% Formula

The rent increase calculation under Civil Code §1947.12(b) works as follows:

Step 1: Identify the Applicable CPI-U Index

California uses the Consumer Price Index for All Urban Consumers (CPI-U), not the general U.S. national CPI. The statute specifies two regional indices:

• San Francisco Bay Area Region: Properties in the Bay Area (Alameda, Contra Costa, Marin, San Mateo, Santa Clara, and Sonoma counties) use the CPI-U for the San Francisco-Oakland-San Jose area.
• Los Angeles Region: Properties in Southern California (Kern, Kings, Los Angeles, Orange, Tulare, and Ventura counties) use the CPI-U for the Los Angeles-Long Beach-Anaheim area.
• All other counties: Properties in all other regions use the CPI-U for the U.S. city average (published by the Bureau of Labor Statistics).

You can find current CPI-U data at the Bureau of Labor Statistics website (bls.gov). The data is released monthly; for rent increase calculations, you use the year-over-year percentage change for the 12-month period ending in the month prior to the rent increase notice.

Step 2: Add 5% to the Applicable CPI-U

Once you have identified the correct regional CPI-U, add 5 percentage points to the year-over-year change. For example:

• If the San Francisco Bay Area CPI-U year-over-year change is 2.1%, then CPI plus 5% = 2.1% + 5% = 7.1%
• If the Los Angeles CPI-U year-over-year change is 3.4%, then CPI plus 5% = 3.4% + 5% = 8.4%

Step 3: Apply the Lesser of 5% or CPI Plus 5%

Compare the CPI plus 5% figure to 5%. Whichever is lower is your maximum allowable rent increase. Examples:

Year-Over-Year CPI-U	CPI + 5%	Maximum Allowable Increase	Limiting Factor
0.8%	5.8%	5.0%	5% cap applies
2.1%	7.1%	5.0%	5% cap applies
-0.5% (deflation)	4.5%	4.5%	CPI + 5% applies

Practical Calculation Example for 2026 Rent Increases

Assume you are a self-managing landlord with a 12-unit apartment building in the Los Angeles area. Your current rent is $1,600 per month. The tenant's lease renews on January 15, 2027. You must provide 30 days' notice by December 16, 2026.

In October 2026, you check the Bureau of Labor Statistics website and find that the Los Angeles CPI-U for September 2026 (the most recent month available) shows a year-over-year increase of 2.3%.

Calculation:

• CPI-U (Los Angeles, September 2026 year-over-year): 2.3%
• CPI plus 5%: 2.3% + 5% = 7.3%
• Lesser of 5% or CPI plus 5%: Lesser of 5% and 7.3% = 5%
• Current rent: $1,600
• Maximum new rent: $1,600 × 1.05 = $1,680

You may increase the rent to a maximum of $1,680 per month. You could also increase to $1,650, $1,670, or any amount up to $1,680—the law sets a ceiling, not a requirement to increase by the full amount. However, you must send notice on or before December 16, 2026, specifying the new rent amount and effective date.

Notice Requirements and Timing Compliance

California Civil Code §1947.12(d) requires that rent increase notices meet strict procedural requirements. Failure to comply with notice rules does not invalidate the increase, but it provides grounds for tenant lawsuits and may result in penalties.

30-Day Notice Requirement

You must provide written notice at least 30 days before the rent increase takes effect. The notice period begins on the date you deliver or mail the notice, not the date the tenant receives it. For tenancies with renewal dates (e.g., January 15), count 30 calendar days backward to determine the deadline (e.g., December 16).

For month-to-month tenancies, the notice must terminate the tenancy as of the next regular rental payment date, or 30 days from the notice date, whichever is later (California Civil Code §1946).

Required Notice Content

The notice must include all of the following:

• The new rental rate
• The date the increase becomes effective
• The amount of the increase (in dollars and/or percentage)
• The method used to calculate the increase (e.g., "5% AB 1482 maximum" or "CPI-U plus 5% formula")
• A statement that the tenant may contact local legal aid or tenant rights organizations (required by statute)
• Language informing the tenant of the reason for the increase (if applicable)

California does not mandate a specific form, but using a standardized written notice protects you. Email, text message, or posting are insufficient; you must use personal delivery or certified mail with return receipt.

Timing Triggers and Renewal vs. Month-to-Month

Tenancy Type	Notice Deadline	Effective Date of Increase
Fixed-term lease expiring Dec 31, 2026	By Dec 1, 2026 (30 days before)	Jan 1, 2027 (lease renewal date)
Month-to-month tenancy, rent due on the 1st	By Sept 1, 2026 (30 days before Oct 1)	Oct 1, 2026 (next rental payment date)
Fixed-term lease with automatic conversion to month-to-month	30 days before the end of the fixed term or before the next rental payment date	First rental payment date after 30-day notice period

Do not send rent increase notices during a tenant's fixed-term lease (except at renewal). Increasing rent mid-lease violates the lease terms and is legally unenforceable under California law, regardless of the AB 1482 formula.

Prohibited Conduct and Penalty Exposure

AB 1482 creates civil liability for landlords who violate the statute. California Civil Code §1947.12(e) explicitly prohibits increases above the legal limit and specifies remedies available to tenants.

What Constitutes a Violation

• Increasing rent above the 5% or CPI plus 5% threshold — even by $1
• Increasing rent without 30 days' written notice — or without proper notice content
• Retaliatory increases in response to tenant complaints, repair requests, or protected conduct — California Civ. Code §1947.7 creates a rebuttable presumption of retaliation if an increase occurs within 180 days of protected activity
• Increasing rent on units where a new tenant is charged above the prior tenant's rate by more than 10% plus inflation — this "just cause" requirement under AB 1482 applies when a unit is re-rented

Penalties and Damages

Tenants can sue for violations of AB 1482. Possible damages include:

• Actual damages: The amount of rent overcharged (difference between the illegal increase and the allowable increase, multiplied by the number of months)
• Statutory penalty: Up to $2,500 per violation (California Civil Code §1947.12(e)(1))
• Attorney fees and costs: The prevailing tenant can recover all reasonable attorney fees and litigation costs
• Treble damages: In some cases involving egregious conduct, courts have awarded three times actual damages plus penalties

Example: You increase a tenant's rent by $200 (exceeding the allowable $80 increase by $120). The tenant sues and wins. Damages could include:

• $120 × 12 months = $1,440 in actual overcharges
• Up to $2,500 statutory penalty
• Attorney fees (potentially $5,000–$15,000 or more)
• Total liability: $8,940–$19,440 or higher

These penalties deter violations and make compliance financially critical for self-managing landlords.

CPI Data Sources and Annual Updates for 2026-2027

To stay compliant, you must use accurate, official CPI-U data. The Bureau of Labor Statistics publishes the following indices for California regions:

• San Francisco-Oakland-San Jose (Series APUS49749906000): Released monthly at bls.gov
• Los Angeles-Long Beach-Anaheim (Series APUS31849906000): Released monthly at bls.gov
• U.S. City Average (Series CUUR0000SA0): For all other California counties

The year-over-year percentage change is calculated as follows:

Year-over-year % change = (Current month CPI-U − Same month prior year CPI-U) ÷ Same month prior year CPI-U × 100

For rent increases effective in 2027, use the CPI-U data released in January 2027 (which reflects December 2026 data). Do not use preliminary or revised data; use the "not seasonally adjusted" series published by BLS for consistency with legislative intent.

Documentation and Audit Trail

Maintain detailed records of your rent increase calculations:

• CPI-U source and date downloaded: Screenshot or print the BLS website showing the index value and date
• Calculation worksheet: Document the formula: (CPI-U % + 5%), comparison to 5%, and final allowable increase
• Notice copies: Keep proof of delivery (certified mail receipts, signed delivery confirmations, or email records if tenant accepts electronic notice)
• Tenant correspondence: Any tenant questions or disputes regarding the increase
• Lease terms at time of increase: Copy of the lease agreement showing the current rent and renewal date

If a tenant later challenges the increase, this documentation proves you calculated the amount correctly and provided proper notice. Without it, you face a burden-shifting problem: the tenant alleges violation, and you must prove compliance.

Interaction With Local Rent Control Ordinances

Some California cities have their own rent control laws that predate AB 1482, including Los Angeles (RSO), San Francisco (SFRO), Oakland, and Berkeley. If your property is subject to local rent control, you must comply with whichever restriction is more favorable to tenants—i.e., the lowest allowable increase.

Example: Los Angeles RSO permits a 3% increase in 2026. AB 1482 permits 5%. You must increase by no more than 3% because the local ordinance is more restrictive.

Review your city's rent control website or local municipal code to determine whether your property is subject to a local ordinance. Some cities have exemptions for new construction or single-family homes that differ from AB 1482.

Retaliation and "Just Cause" Limitations

Even if you calculate an allowable increase correctly, AB 1482 contains additional restrictions on when you can increase rent. California Civil Code §1947.7 prohibits retaliatory rent increases within 180 days after a tenant:

• Requests repairs or reports a code violation to the landlord or government agency
• Complains to a housing code enforcement agency about habitability defects
• Organizes or participates in a tenant's organization or labor activity
• Files a complaint with a government agency regarding the premises
• Initiates or participates in a rent strike or escrow action

If you increase rent within 180 days of such conduct, the statute creates a rebuttable presumption of retaliation. You must prove the increase was based on legitimate, non-retaliatory reasons (e.g., inflation, property improvement).

Best practice: Do not increase rent for any tenant who has made repair requests or filed complaints in the past 180 days, even if the increase is legally allowable. The litigation risk and penalties outweigh the additional revenue.

Compliance Checklist for AB 1482 Rent Increases

Before increasing rent, complete this checklist:

• ☐ Verify the property is covered by AB 1482 (not exempt as single-family, new construction, or luxury)
• ☐ Verify the tenancy is not subject to a more restrictive local ordinance
• ☐ Confirm the tenant has not made repair requests or filed complaints in the past 180 days
• ☐ Download the current year-over-year CPI-U data from bls.gov for the correct regional index
• ☐ Calculate CPI plus 5% and compare to 5% ceiling; document both figures
• ☐ Determine the maximum allowable increase amount (in dollars)
• ☐ Verify the tenancy end date or next rental payment date (for month-to-month)
• ☐ Calculate the 30-day notice deadline and confirm it is met
• ☐ Draft the notice including new rent amount, effective date, increase percentage, and calculation method
• ☐ Deliver the notice by certified mail, personal delivery, or mutually agreed electronic means
• ☐ Retain proof of delivery (signed receipt, screenshot, or tracking confirmation)
• ☐ Keep copies of the notice, CPI calculation worksheet, and delivery proof in your file

If you use a property management platform with compliance tracking, ensure it is configured for your property's regional CPI index and automatically calculates the correct allowable increase based on current data. Platforms that hard-code a 5% increase without checking CPI data create liability.

Frequently Asked Questions

Q: Can I calculate rent increases based on national CPI rather than the regional index?

A: No. AB 1482 explicitly requires use of the Consumer Price Index for All Urban Consumers (CPI-U) for your specific region. Using national CPI instead, or using an alternative inflation measure (PPI, PCE), violates the statute and exposes you to penalties. The regional indices are published monthly by the Bureau of Labor Statistics and are free to access.

Q: What happens if I accidentally send a rent increase notice with the wrong calculation?

A: If the notice overstates the allowable increase, the tenant can dispute it and potentially sue for the difference. The statute does not provide a "safe harbor" for good-faith mistakes. You must withdraw the notice in writing and send a corrected notice with a new 30-day deadline. If the tenant pays the higher amount, you may owe refunds plus penalties and attorney fees.

Q: Can I increase rent twice in one year if I split the allowable increase?

A: No. AB 1482 limits increases to once per 12 months for fixed-term leases and once per year (on the anniversary date) for month-to-month tenancies. You cannot increase rent in January and again in July in the same year, even if each increase is individually compliant. This restriction prevents circumventing the annual cap.

Q: Are there any lease language I should add to comply with AB 1482?

A: Yes. Include a clause stating: "Annual rent increases are limited by California Civil Code §1947.12 (AB 1482) to the lesser of 5% or the Consumer Price Index for [region] plus 5%, calculated annually. Tenant will receive 30 days' written notice of any increase." This language informs tenants of the cap and protects you by demonstrating intent to comply. Have a qualified attorney review your lease templates.

Q: If CPI is negative in a year (deflation), can I decrease rent under AB 1482?

A: No. AB 1482 sets a ceiling on increases, not a floor. Negative CPI means the allowable increase is lower (e.g., -0.5% + 5% = 4.5%), but you have no right to decrease rent. Decreasing rent would be a separate voluntary action outside the statute's scope.

Key Takeaways for Your Portfolio

AB 1482's CPI plus 5% formula is precise, data-driven, and enforceable. Self-managing landlords who get the calculation wrong face substantial penalties and potential tenant litigation. The statute's compliance requirements are technical:

• Use the correct regional CPI-U index (Bay Area, Los Angeles, or U.S. city average)
• Calculate year-over-year percentage change accurately
• Apply the lesser of 5% or CPI plus 5%
• Provide 30 days' written notice with proper content
• Avoid rent increases on tenancies with recent repair requests or complaints (retaliation risk)
• Document all calculations and delivery of notice
• Check whether your property is exempt or subject to a more restrictive local ordinance

If your portfolio spans multiple properties across different regions, tracking different CPI indices and calculation deadlines becomes complex. LeaseBase's compliance tools automate CPI lookups, calculate the maximum allowable increase, and flag which properties are exempt or subject to local ordinances. This eliminates manual calculation errors and ensures notices meet statutory deadlines.

For detailed tracking of your portfolio's rent increase history and tenant communication, lease operations software creates a centralized audit trail. When disputes arise (and some will), your documentation proves compliance before attorneys become necessary.

Disclaimer: This article is for informational purposes only and does not constitute legal advice. Consult a qualified attorney for guidance specific to your situation. California landlord-tenant law is complex and changes frequently; verify all information against current statutes before taking action. LeaseBase does not provide legal advice or guarantee compliance with all applicable laws.