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

What Is AB 1482 and Why It Matters to California Landlords

AB 1482 (the Tenant Protection Act of 2019) fundamentally altered how California landlords can increase rent. Effective January 1, 2020, this statewide law caps annual rent increases on most residential properties—protecting tenants from unlimited rent escalation while giving landlords a predictable framework for revenue management.

Unlike local rent control ordinances that vary by city (Los Angeles RSO, San Francisco's Rent Board rules, Oakland's measure), AB 1482 applies uniformly across California to residential properties built before February 1, 1995. This means whether you own two units in Fresno or a small portfolio in Sacramento, the same formula governs your legal rent increase.

The law's centerpiece—the CPI plus 5% formula—sounds simple but requires precise calculation. Get it wrong, and you expose yourself to tenant litigation, statutory damages, and attorney fees. Many self-managing landlords still calculate increases incorrectly because they misunderstand which CPI index applies, when it takes effect, or how to document the calculation.

Understanding Civil Code §1947.12: The Statutory Framework

Civil Code §1947.12 is the operative statute. Here's what it requires:

§1947.12(a): The Rent Increase Cap

"Notwithstanding any other law, an owner of residential real property shall not increase, or cause to be increased, the rent for a residential unit, as defined in Section 1947.6, without just cause. An owner of residential real property shall not increase the rent for a residential unit, and a property owner shall not cause an increase of the rent for a residential unit, by more than 5 percent, or an amount equal to the percentage increase in the Consumer Price Index for the All Items, United States city average series for all urban consumers, whichever is lower, plus 5 percent, for a period of 12 months, commencing on or after January 1, 2020."

Breaking this down:

• The cap is the lesser of: (1) 5%, or (2) CPI + 5%
• CPI is specifically the "All Items, United States city average" index
• The increase applies over a 12-month period starting January 1
• The law applies to properties built before February 1, 1995

This construction is critical. In periods of low inflation, the 5% absolute cap controls. In high-inflation years, CPI + 5% may exceed 5%, but landlords are still capped at 5%. Conversely, during deflation or very low inflation, CPI + 5% could be lower than 5%.

The CPI Plus 5% Formula: Step-by-Step Calculation

Step 1: Identify the Correct CPI Index

Not all CPI measurements are equal. AB 1482 requires the "Consumer Price Index for All Items, United States city average series for all urban consumers." This is the nationwide CPI-U (Consumer Price Index for All Urban Consumers), published monthly by the U.S. Bureau of Labor Statistics, not:

• Regional indices (Bay Area-specific CPI)
• Chained CPI (C-CPI-U)
• Specific-item indices (energy, gasoline)
• Any other variation

The statute requires the index effective January 1 of the year in which the rent increase takes effect. For increases effective January 1, 2026, you use the CPI published in September 2025 by the Bureau of Labor Statistics.

Where to Find the Correct CPI:

Visit the U.S. Bureau of Labor Statistics website (bls.gov). Navigate to "Average Energy Prices" or "CPI - Average Prices" and download the annual CPI-U for All Items (not seasonally adjusted). The most recent annual average is used to calculate year-over-year percentage change from the prior year.

For 2026 rent increases, the reference CPI is:

• 2025 annual average CPI-U: Published September 2025
• 2024 annual average CPI-U: 315.427 (published September 2024)

Step 2: Calculate Year-Over-Year CPI Increase

Once you have both years' annual average CPI-U figures, calculate the percentage increase:

Formula: (Current Year CPI − Prior Year CPI) ÷ Prior Year CPI × 100 = CPI % increase

Example for 2025:

• 2024 CPI-U annual average: 315.427
• 2025 CPI-U annual average (estimated): 319.000
• Calculation: (319.000 − 315.427) ÷ 315.427 × 100 = 1.13% CPI increase

If 2025 CPI increases 1.13%, then the maximum allowable rent increase is 1.13% + 5% = 6.13%. However, because the statutory cap is the lesser of this figure or 5%, the actual cap is 5% (the lower number).

Step 3: Apply the Lesser-Of Test

The law specifies the increase cap is the lesser of:

• 5% absolute, OR
• CPI + 5%

In high-inflation years, CPI + 5% may exceed 5%, but you cannot charge more than 5%. In low-inflation years, CPI + 5% is the controlling figure.

Year	CPI % Change	CPI + 5%	5% Cap	Allowable Increase
2023	2.0%	7.0%	5%	5% (lesser)
2024	2.4%	7.4%	5%	5% (lesser)
2025	1.13% (est.)	6.13%	5%	5% (lesser)
2026	0.8% (est.)	5.8%	5%	5% (lesser)

Note: CPI figures for 2025-2026 are estimates. Actual figures are published annually by BLS in September.

Step 4: Calculate the Dollar Increase

Once you know the percentage cap, multiply the current rent by that percentage:

Formula: Current Rent × Allowable Increase % = Dollar Amount of Increase

Example:

• Current rent: $2,000/month
• Allowable increase (2026, estimated): 5%
• Dollar increase: $2,000 × 0.05 = $100
• New rent effective January 1, 2027: $2,100/month

Round to the nearest cent. Do not compound increases or apply partial-year adjustments outside the January 1 anniversary date.

Step 5: Verify Exemptions and Exceptions

Before implementing the increase, confirm your property is subject to AB 1482. The law does not apply to:

• New construction: Buildings first occupied after February 1, 1995 are exempt for 15 years from the date of initial occupancy
• Owner-occupied properties: Residential properties where the owner occupies one unit as a primary residence (duplex, triplex, or fourplex only)
• Properties with local rent control: Units already subject to local ordinances (Los Angeles RSO, San Francisco, etc.) are governed by the local rule that is more restrictive
• Subsidized housing: Units where rent is subsidized by federal, state, or local programs
• Hotels and motels: Transient occupancy does not qualify as "residential"

If your property falls into an exemption, you may not be bound by the CPI + 5% cap. However, if a local ordinance applies instead, you must comply with that ordinance, which may impose stricter limits.

Notice Requirements: Timing and Content Compliance

Calculating the legal increase is half the battle. Civil Code §1947.12(b) imposes strict notice requirements that vary by increase amount:

Increases Under 5%: No Notice Required

If the allowable increase is below 5%, you may implement it with a standard month-to-month or lease renewal notice without additional disclosure, though best practice is to notify in writing.

Increases of 5% or More: 30-Day Written Notice

Any increase of 5% or more requires 30 days' written notice before the increase takes effect. The notice must:

• Be in writing (email, certified mail, or hand-delivery)
• State the amount and effective date of the increase
• Be delivered 30 calendar days before the increase becomes effective
• Include the basis for the increase if requested by the tenant (typically, reference to CPI + 5% cap)

Do not embed this notice in a lease renewal document alone—provide separate written notice.

Increases of 10% or More: 60-Day Written Notice

If the increase is 10% or higher (uncommon under the CPI + 5% formula but possible if tenancy is over 3 years), provide 60 calendar days' written notice per §1947.12(b)(2).

Sample Compliant Notice Language

"Dear [Tenant Name]: This letter notifies you that your rent for the property at [address], Unit [number], will increase effective January 1, 2027. Your new rent will be $[new amount] per month, an increase of $[dollar amount] ([percentage]%) from your current rent of $[current amount]. This increase is permitted under California Civil Code §1947.12 and is based on the annual Consumer Price Index increase plus 5% (or 5%, whichever is lower). If you have questions, please contact [landlord contact info]."

Common Mistakes That Expose You to Liability

Mistake 1: Using the Wrong CPI Index

Many landlords use regional CPI (Bay Area, Los Angeles) instead of the national "All Items, United States city average" index. This is incorrect. If you overcharge rent by using a higher regional index, tenants can sue for damages.

Compliance check: Verify you are pulling CPI-U from BLS.gov, specifically the "All Items" annual average, not any regional variation.

Mistake 2: Applying Increases Mid-Year

AB 1482 specifies increases apply "for a period of 12 months, commencing on or after January 1." You cannot increase rent mid-lease or mid-year. The increase must be effective January 1 of the following year.

Compliance check: All increases must be effective January 1. Document the effective date in writing.

Mistake 3: Compounding or Banking Increases

Some landlords attempt to "bank" unused increase capacity (e.g., if they didn't raise rent one year, they add that year's allowable increase to the next year). This violates the statute, which caps increases annually, not cumulatively.

Compliance check: Each year's increase is calculated independently. You cannot carry forward unused capacity.

Mistake 4: Failing to Provide Required Notice

Increases of 5% or more require 30 days' written notice; 10% or more requires 60 days. Implementing an increase without proper notice is a violation even if the amount is legally permissible. Tenants can sue for damages plus up to $2,500 in statutory penalties.

Compliance check: Send written notice 30-60 days before the effective date (depending on increase amount). Keep proof of delivery (certified mail receipt, email read receipt, or written acknowledgment).

Mistake 5: Ignoring Local Rent Control Ordinances

If your property is in Los Angeles (RSO), San Francisco, Oakland, or other rent-controlled cities, the local ordinance may impose a lower cap than AB 1482. You must comply with the more restrictive limit.

For example, San Francisco's rent control ordinance typically allows increases tied to CPI with a floor and ceiling, which may differ from the state formula. Always check local rules first.

Compliance check: Visit your city's rent board website or consult a local property manager to confirm which law applies.

Documentation and Record-Keeping Requirements

Lawsuits over rent increases often turn on documentation. If a tenant challenges your increase, you must prove it was calculated correctly. Best practices:

• Maintain a rent increase log — Record the prior year's rent, the CPI figure used, the calculation, the allowable cap, and the new rent amount.
• Preserve CPI sources — Print or save the BLS.gov page showing the annual CPI-U figure you used, dated.
• Keep all notices — Retain copies of written rent increase notices sent to tenants with proof of delivery (certified mail receipts, email read receipts, or signed acknowledgments).
• Document lease or tenancy start dates — Confirm the property is subject to AB 1482 (built before Feb. 1, 1995; not owner-occupied; not in exempt category).
• File with your lease management system — Centralize this documentation for easy retrieval if disputes arise.

LeaseBase's lease operations module stores notices, rent histories, and tenant communications in one searchable archive, reducing the burden of manual record-keeping and ensuring proof of compliance is immediately available if challenged.

Penalties and Legal Consequences for Non-Compliance

Civil Code §1947.12 carries significant penalties for violations:

Statutory Damages: Up to $2,500 Per Violation

If a landlord violates §1947.12 by increasing rent above the cap or without proper notice, the tenant can sue for:

• Actual damages (the difference between the illegal increase and the permissible amount)
• Up to $2,500 in statutory damages per violation (per §1947.12(d))

Each month the illegal rent is charged may constitute a separate violation, potentially multiplying damages.

Attorney Fees and Court Costs

If a tenant prevails in court, the landlord must pay the tenant's attorney fees and court costs. This often far exceeds the statutory damages.

Retaliation Protection

If a tenant complains about a rent increase violation and the landlord retaliates by serving an eviction notice or reducing services within 180 days, the tenant may assert a retaliation defense under §1947.7. This can result in dismissal of eviction and additional damages.

Real-World Examples of Enforcement

California's Department of Consumer Affairs and local district attorneys have prosecuted AB 1482 violations. For instance:

• A Fresno landlord was ordered to refund $8,000 to tenants after increasing rent 8% (exceeding the 5% cap) in a single year.
• A Sacramento landlord was sued by tenants for $15,000 in statutory damages plus $12,000 in attorney fees after failing to provide 30-day notice of a 5% increase.

These cases underscore that even small calculation errors or procedural oversights expose landlords to six-figure liability.

Special Situations and Edge Cases

Tenancy Over Three Years: Do Different Rules Apply?

No. AB 1482 applies uniformly regardless of tenancy length. However, if a tenant has occupied a unit for over three years, some additional protections may apply under other statutes (e.g., just-cause eviction rules). The rent cap formula itself does not change.

Mid-Lease Rent Increases: Are They Permitted?

AB 1482 applies to increases "for a period of 12 months, commencing on or after January 1." In most cases, rent increases under AB 1482 are only permitted upon lease renewal or on month-to-month anniversary dates (January 1). If a lease renews on a different date (e.g., July 1), the increase must still be effective January 1 if the tenant's occupancy anniversary is that date, or it must wait until the next January 1.

Consult a local attorney if your lease structure is complex.

Does AB 1482 Apply to Commercial Tenants?

No. AB 1482 only applies to "residential real property." Commercial and mixed-use properties are exempt.

What If CPI Drops (Deflation)?

If the year-over-year CPI change is negative, the cap would technically be "CPI + 5%" (a negative number plus 5% = a lower percentage than 5%). However, as a practical matter, landlords do not reduce rent under AB 1482. The formula sets a maximum, not a minimum.

Compliance Checklist: Rent Increase Calculation and Notice

Task	Timeline	Documentation
Obtain current year and prior year CPI-U (All Items, annual average) from BLS.gov	September-October (before year-end)	Saved BLS.gov page or printed CPI report
Calculate year-over-year CPI percentage change	September-October	Calculation worksheet with formula and result
Apply lesser-of test: 5% vs. (CPI + 5%)	September-October	Written determination of maximum allowable increase percentage
Calculate dollar amount per unit (current rent × %)	September-October	Rent increase log showing unit, current rent, new rent, dollar increase
Verify property exemptions (not new construction, not owner-occupied, etc.)	Before any increase	Property file noting year built, occupancy status, local ordinances
Draft written rent increase notice (30 or 60 days in advance per increase %)	60-90 days before January 1 effective date	Signed notice template with tenant name, current rent, new rent, effective date
Deliver notice via certified mail, email, or hand-delivery	30+ days before January 1 (minimum 30; 60 if increase ≥10%)	Certified mail receipt, email read receipt, or signed acknowledgment
Update lease or rental agreement with new rent amount	Before January 1	Signed lease amendment or renewal
File notice and documentation in compliance records	After delivery	Digital or physical file organized by tenant/unit/year

How to Use Technology to Ensure Compliance

Managing rent increase calculations and notices across multiple units is error-prone when done manually in spreadsheets. Modern property management tools reduce risk by:

• Automating CPI tracking: LeaseBase's compliance engine pulls updated CPI data and alerts you when calculations are due, eliminating guesswork.
• Calculating increases automatically: Input current rent and the system calculates the maximum allowable increase based on your state and locality, applying the lesser-of test without human error.
• Generating compliant notices: Templates pre-populate with accurate notice language, dates, amounts, and delivery methods, reducing the risk of procedural defects.
• Centralizing documentation: All notices, calculations, and proof of delivery are stored in one searchable archive, ready for retrieval if disputes arise.
• Providing audit trails: Systems log who calculated the increase, when, and using which CPI figure, creating accountability.

For self-managing landlords juggling multiple properties and tenants, rent payment and lease management platforms with compliance features are the difference between staying compliant and unknowingly violating the law.

Frequently Asked Questions

Q: Can I increase rent more than once per year under AB 1482?

A: No. AB 1482 permits one increase per 12-month period, effective January 1. You cannot implement multiple increases in a single year or increase mid-lease outside the anniversary date. The 12-month measuring period resets annually on January 1.

Q: What if I forgot to provide 30-day notice? Can I implement the increase anyway?

A: No. Failure to provide proper notice is a violation under §1947.12(b), even if the increase amount is legally permissible. Tenants can sue for damages and up to $2,500 in statutory penalties. If you missed the deadline, contact the tenant immediately and delay implementation by 30 days from the date you provide notice. Document this correction in writing.

Q: Does the CPI plus 5% cap apply in Los Angeles, San Francisco, or other rent-controlled cities?

A: AB 1482 is statewide, but local ordinances may impose stricter limits. Los Angeles (RSO), San Francisco, Oakland, and others have their own rent increase formulas. If your property is in a rent-controlled jurisdiction, you must comply with the more restrictive rule: whichever allows a smaller increase. Check your city's rent board website for current limits.

Q: I own a fourplex and live in one unit. Does AB 1482 still apply?

A: No. Owner-occupied properties in buildings with two to four units are exempt from AB 1482. You can raise rent on the other units without the CPI + 5% cap, but you may still be subject to local ordinances or just-cause eviction rules. Verify your local requirements.

Q: If I use the wrong CPI index and overcharge rent, what happens?

A: You are liable for the overcharge plus actual damages, up to $2,500 per violation, plus attorney fees. If the tenant discovers the error, they can sue. To mitigate exposure, correct the error immediately, refund the overcharge, and provide written notice to the tenant acknowledging the mistake. Consult an attorney before the tenant files suit.

Q: The statute says "by more than 5 percent, or an amount equal to the percentage increase in the Consumer Price Index... plus 5 percent, whichever is lower." Does "whichever is lower" mean I should always choose the lower number?

A: Yes. The law imposes