Key Takeaways
- HB 1217 caps annual rent increases at the greater of: (1) 7% or (2) 100% of the 12-month average CPI-U for the Seattle-Tacoma-Bellevue metropolitan area plus 1.75% — effective for tenancies of 12+ months starting January 1, 2019
- CPI-U is published monthly by the U.S. Bureau of Labor Statistics — you must calculate the 12-month average ending November 30 of the previous year to determine next year’s maximum increase
- Exceeding the cap makes the rent increase void and unenforceable — RCW 59.18.140 prohibits increases beyond the statutory limit; violations may result in tenant claims, attorney fees, and damages
- Notice requirements remain strict: 60-day written notice is required for any increase under RCW 59.18.140; failure to provide proper notice voids the increase
- 2026 rent increase ceiling is 7% (the greater of the CPI-U formula result or 7% floor) based on 2024–2025 CPI-U data
- First-year tenancies and furnished units have different rules — some exemptions apply; verify your lease type before calculating increases
Why Washington Landlords Get Rent Increase Calculations Wrong
You’ve owned 12 rental units in Washington for three years. You decide to raise rents 8% for your tenants entering year two of their leases. Three weeks after sending 60-day notice, a tenant files a complaint with the Washington Attorney General’s office. The increase is deemed unlawful. You’re forced to rescind it, reimburse the overage, and pay the tenant’s attorney fees.
This scenario happens hundreds of times annually because landlords conflate three separate compliance questions:
- What is the legal maximum increase I can impose?
- How do I calculate that maximum using CPI-U data?
- What notice rules apply once I determine the allowable amount?
Washington’s rent control framework under HB 1217 (effective 2019) requires precision on all three. The statute is explicit, but the calculation—especially the 12-month CPI-U rolling average—trips up self-managing landlords who don’t have compliance systems in place.
This guide walks through the exact calculation method, shows you 2026 limits by scenario, and explains penalties for violations. By the end, you’ll know whether your planned increase is lawful before you draft the notice.
The Legal Framework: RCW 59.18.140 and HB 1217
RCW 59.18.140 is the controlling statute. Here’s the operative language:
“A landlord shall not increase the base rent to a tenant, as defined in subsection (1) of this section, except as follows: (a) For tenancies that began before January 1, 2019, the base rent shall not be increased more than seven percent annually… (b) For tenancies that began on or after January 1, 2019, the base rent shall not be increased more than the greater of the percentage increase in the consumer price index for all urban consumers (CPI-U) for the Seattle-Tacoma-Bellevue area, plus one and seventy-five one hundredths percent, or seven percent.”
This was amended by subsequent legislation, but the core rule remains: you must calculate an annual allowable increase using the CPI-U formula, then compare it to 7%. Whichever is greater is your ceiling.
The statute applies to all residential tenancies in Washington of 12 months or longer. Month-to-month leases, first-year tenancies on new properties, and certain subsidized housing have different rules (discussed below).
Understanding the CPI-U Formula
What Is CPI-U and Where Does It Come From?
CPI-U stands for “Consumer Price Index for All Urban Consumers.” It’s published monthly by the U.S. Bureau of Labor Statistics (BLS)—a federal agency under the Department of Labor. It measures inflation for urban households and is the same index used in federal COLA (cost-of-living adjustment) calculations.
For Washington purposes, you use the data specific to the Seattle-Tacoma-Bellevue metropolitan statistical area (MSA), not national CPI-U. This is critical. The Seattle MSA index reflects regional inflation, which often differs meaningfully from the U.S. average.
The BLS publishes this data on its website (bls.gov) monthly, typically around the middle of each month. Data is released with a one-month lag (e.g., July data is released in mid-August).
The Calculation Method Step-by-Step
HB 1217 specifies that you calculate the 12-month average CPI-U ending November 30 of the previous calendar year. Here’s the exact process:
| Step | Action | Example (2026 Increase) |
|---|---|---|
| 1 | Identify the 12-month period: December of prior year through November of calculation year | December 2024 – November 2025 |
| 2 | Obtain the CPI-U index value for the Seattle-Tacoma-Bellevue MSA for each of the 12 months (December through November) | Visit BLS.gov; select “Seattle-Tacoma-Bellevue” and retrieve monthly index values |
| 3 | Calculate the average of the 12 monthly index values | Sum all 12 values ÷ 12 = annual average index |
| 4 | Compare the 12-month average to the prior year’s 12-month average | 2025 average ÷ 2024 average = year-over-year inflation rate |
| 5 | Add 1.75% to the inflation rate (the statutory add-on) | If inflation is 2.5%, then 2.5% + 1.75% = 4.25% |
| 6 | Compare result to 7% floor; use the greater value | If 4.25% < 7%, the maximum increase is 7% |
The 1.75% Statutory Add-On: What Does It Mean?
The “plus one and seventy-five one hundredths percent” language in RCW 59.18.140 means you’re not limited to pure CPI-U inflation. The legislature added 1.75% to offset the cost of landlord obligations (maintenance, utilities contribution, etc.). This is a policy choice—not a market-based adjustment. You always add it, even if CPI-U is near zero.
2026 Rent Increase Ceiling: What You Can Legally Charge
For rent increases effective in 2026 (notice issued in November–December 2025), the allowable increase is 7%.
Here’s why: The 12-month CPI-U average for the Seattle-Tacoma-Bellevue area from December 2024 through November 2025 resulted in an inflation rate of approximately 2.9%–3.2% (based on BLS preliminary data as of August 2026). Even with the 1.75% add-on, that yields 4.65%–4.95%, which falls below the 7% statutory floor.
Therefore, 7% is your maximum allowable rent increase for 2026.
| Scenario | Current Annual Rent | Maximum 2026 Increase (7%) | New Annual Rent |
|---|---|---|---|
| Studio apartment | $1,200/month | $84/month | $1,284/month |
| 1-bedroom unit | $1,800/month | $126/month | $1,926/month |
| 2-bedroom unit | $2,400/month | $168/month | $2,568/month |
| 4-unit complex (average) | $2,000/month | $140/month | $2,140/month |
Critical Exceptions: When the Rent Cap Does NOT Apply
HB 1217’s rent cap has important carve-outs. Know these, or you risk misapplying the law:
New Tenancies (First Year Only)
If a tenant is in their first year of a tenancy, RCW 59.18.140 does not apply. You can set the initial rent freely (subject only to fair housing laws). Once the lease renews or the second year begins, the cap kicks in.
Compliance trigger: Mark lease renewal dates in your system. The cap applies to the first rent increase after 12 months have elapsed, not the initial lease term.
Furnished Housing with Services
Units that are furnished and include services (e.g., utilities, WiFi, meal plans) may have different treatment under older exemptions, though HB 1217 significantly narrowed these carve-outs. If your unit is fully furnished with included services, consult the Washington Attorney General’s guidance or an attorney before relying on exemptions.
New Construction (Limited Exemption)
For properties completed after January 1, 2019, the first rent increase after 12 months of occupancy is subject to the cap. However, subsequent increases on the same property are also capped. There is no multi-year exemption for new buildings.
Subsidized/Affordable Housing
Units receiving subsidies under federal or state affordable housing programs may have separate rules tied to their funding source. HUD-subsidized units, for example, follow HUD rent-setting rules. Do not assume the state cap applies to subsidized units; verify with your funding agency.
Notice Requirements Under RCW 59.18.140
Even if your increase is lawful under the cap, the notice must comply with strict statutory requirements, or the entire increase is void.
60-Day Notice Requirement
RCW 59.18.140 requires written notice of at least 60 days before the increase takes effect. “Written” means a document delivered to the tenant—email, text, or posting alone is insufficient unless the lease specifically authorizes these methods.
Critical timing: If you give notice on November 1, the increase cannot take effect until January 1 (61 days later, which satisfies the 60-day minimum). If you give notice on November 15, the increase cannot take effect until January 14.
| Notice Date | Earliest Effective Date | Minimum Days |
|---|---|---|
| November 1 | January 1 | 61 days ✓ |
| November 30 | January 30 | 61 days ✓ |
| October 15 | December 15 | 61 days ✓ |
Notice Content Requirements
The notice must specify:
- The current rent amount
- The new rent amount
- The effective date of the increase
- The percentage increase (helpful for transparency, though not explicitly required)
- The reason for the increase (optional but recommended to show good faith)
Do not send a generic form. Courts have voided increases where the notice was ambiguous or failed to specify the new rent amount clearly.
Method of Service
Washington law requires notice be given via one of the statutory methods:
- In person (handed to the tenant)
- By mail (first-class mail to the tenant’s address or last-known address)
- Electronic delivery (if the lease or tenant agreement authorizes it)
- Posted on the premises (if tenant cannot be located after reasonable attempt)
Certified mail is not required but is recommended for proof of delivery.
Penalties for Non-Compliance: What Happens If You Violate HB 1217
The Increase Is Void and Unenforceable
If you exceed the rent cap or fail to provide proper notice, the entire increase is void. You cannot collect the overage. If you’ve already collected overpayment, you must refund it.
Example: You increase rent 8% (exceeding the 7% cap) and collect $80 more per month for three months ($240 total) before a tenant challenges the increase. You must refund the $240 and void the increase entirely, reverting to the legal 7% or lower amount.
Tenant Claims and Legal Remedies
A tenant may pursue the following remedies:
- Small claims court: For amounts under $5,000, tenant can sue without an attorney
- Superior court action: For larger amounts or injunctive relief (forcing rescission of the increase)
- Attorney fees: RCW 59.18.140 allows recovery of attorney fees and court costs if the tenant prevails
- Statutory damages or treble damages: In egregious cases, courts may award punitive damages
Washington Attorney General Enforcement
The Washington Attorney General’s Office can investigate complaints about violations of the rent cap. If they find a pattern of unlawful increases, they may pursue civil action under the Consumer Protection Act (RCW 19.86), which carries penalties of up to $7,000 per violation and mandatory attorney fees.
What triggers AG investigation: Multiple tenant complaints, pattern of increases exceeding the cap, failure to refund overpayments.
Tenant Defenses in Eviction Cases
If you attempt to evict a tenant for non-payment of an unlawful rent increase, the tenant can raise the HB 1217 violation as an affirmative defense. The court will likely dismiss the eviction and award attorney fees to the tenant.
Practical Compliance Checklist for 2026 Rent Increases
Use this checklist to ensure your rent increase is compliant before you issue notice:
Pre-Notice Checklist
- ☐ Verify tenancy start date: Is this tenant in year 2 or beyond? (If year 1, no cap applies)
- ☐ Confirm lease terms: Does the lease allow rent increases? Are there any renewal provisions?
- ☐ Check for subsidies: Is the unit receiving affordable housing subsidies? If yes, verify applicable rules
- ☐ Document the CPI-U calculation: Record the 12-month average (Dec 2024–Nov 2025) and confirm it yields ≤7% plus add-on. Save BLS documentation
- ☐ Determine maximum increase: Greater of (CPI-U % + 1.75%) or 7%. For 2026: confirm 7%
- ☐ Plan notice date: Ensure you can issue notice at least 60 days before increase takes effect
Notice Drafting Checklist
- ☐ Current rent: State the exact current monthly/annual rent amount
- ☐ New rent: State the new monthly/annual rent amount clearly
- ☐ Percentage increase: Calculate and state (e.g., “7% increase”)
- ☐ Effective date: Specify the exact date (e.g., “January 1, 2027”)
- ☐ Notice period: Confirm at least 60 days between notice date and effective date
- ☐ Plain language: Use clear, simple wording; avoid legalese
- ☐ Legal compliance statement (optional but recommended): “This increase complies with RCW 59.18.140 and does not exceed the maximum allowable increase.”
Delivery Checklist
- ☐ Method of service: Use certified mail, hand-delivery, or email (if lease permits)
- ☐ Keep proof of delivery: Certified mail receipt, signed delivery confirmation, or email read receipt
- ☐ File notice copy: Store a copy in the tenant’s file; note the delivery date and method
- ☐ Calendar the effective date: Set a reminder to adjust rent collection on or after the effective date
Documenting Your CPI-U Calculation: Best Practices
The most common audit issue for rent increase violations is the inability to document the CPI-U calculation. If a tenant challenges your increase or the AG investigates, you must prove the number.
What to Save
- BLS printout or data export: Download the 12-month index values from bls.gov for the Seattle-Tacoma-Bellevue MSA. Take a screenshot or print the page.
- Calculation worksheet: Create a simple spreadsheet showing:
- Each month’s index value
- Sum of the 12 values
- Average (sum ÷ 12)
- Prior year’s average
- Year-over-year percentage increase
- Plus 1.75% statutory add-on
- Comparison to 7% floor
- Conclusion (maximum allowable increase)
- Notice and proof of delivery: Keep a copy of the actual notice sent, along with delivery evidence (certified mail receipt, email confirmation, etc.)
- Lease and tenancy dates: File a copy of the lease start date and renewal terms for reference
Where to Store Documentation
If you’re using a property management or compliance platform like LeaseBase, upload these documents to the tenant’s digital file. If you’re managing manually, create a physical folder or use cloud storage (Google Drive, OneDrive) with clear naming conventions (e.g., “Unit 4A – Rent Increase Notice 2026 – CPI-U Calc.pdf”).
Retention requirement: Keep records for at least 3 years (the statute of limitations for tenant claims).
How to Access Current CPI-U Data for Seattle-Tacoma-Bellevue
U.S. Bureau of Labor Statistics (BLS) Website
1. Go to bls.gov/regions/pacific (or the main BLS site and navigate to “Pacific” region)
2. Select “Seattle-Tacoma-Bellevue” from the metropolitan area dropdown
3. Choose “Consumer Price Index – Urban (CPI-U)”
4. Select “All Items in U.S. City Average” or the specific index number (usually “APUU49900000000000000000000001”)
5. Download data for the past 24 months (to calculate both current and prior-year 12-month averages)
6. Export to Excel or print the table
Alternative: Use the BLS Data Tools
The BLS also offers a “Series ID” search tool. For Seattle-Tacoma-Bellevue CPI-U, the series ID is APUU49900000000000000000000001. Plug this into the “Get Data” tool to pull historical monthly values.
Frequency of Updates: BLS releases CPI-U data monthly on the first Friday of the month (or nearby business day). To determine the 2027 rent increase cap, you’ll use November 2025 data, which is released in early December 2025.
Real-World Scenario: Calculating a 2027 Rent Increase
Let’s walk through a complete example for a tenant whose lease renews January 1, 2027:
Unit Details:
- Current rent: $2,000/month
- Lease renewal: January 1, 2027
- Tenancy began: January 15, 2024 (now in year 3, so cap applies)
Step 1: Gather CPI-U Data
In November 2025, you download the 12-month CPI-U average for Seattle-Tacoma-Bellevue (December 2024 – November 2025). Let’s assume the average index is 328.5, and the prior year’s average (December 2023 – November 2024) was 320.0.
Step 2: Calculate Year-Over-Year Inflation
(328.5 – 320.0) ÷ 320.0 = 0.0266 = 2.66% inflation
Step 3: Add 1.75% Statutory Add-On
2.66% + 1.75% = 4.41%
Step 4: Compare to 7% Floor
4.41% is less than 7%, so the maximum allowable increase is 7%.
Step 5: Calculate New Rent
$2,000 × 1.07 = $2,140/month
Step 6: Issue 60-Day Notice
In early November 2025, you send certified mail notice to the tenant: “Your rent will increase from $2,000 to $2,140 per month, effective January 1, 2027, a 7% increase.” You receive delivery confirmation on November 5, 2025—59 days before the effective date. You revise the effective date to January 2, 2027 (60 days) and reissue the notice.