ADU Rental Income in Seattle, Bellevue & Tacoma: Real 2026 Numbers from 40 Puget Sound Backyards

We pulled rent rolls and occupancy data from 40 completed Puget Sound ADUs built between 2023 and 2025 across Seattle (Ballard, Greenwood, Wallingford, Capitol Hill, West Seattle, Beacon Hill, Rainier Valley), Bellevue (Crossroads, Bel-Red, Lake Hills), Kirkland (Juanita, Rose Hill), Redmond (Education Hill), Renton, Shoreline, Bothell, Everett, and Tacoma (North End, Stadium, Proctor). Every unit was a 480–960 sq ft ADU — detached, garage conversion, or basement — owned by clients who shared 12+ months of actual rent receipts.

We cross-referenced with Zillow Rent Index, Apartments.com Q2 2026, and the King County Assessor. Where our data diverged from public sources by more than 8%, we flagged it — every variance traced back to either a furnished/unfurnished split or an STR-to-long-term conversion mid-lease.

| City | Median Rent (700 sq ft ADU) | Range | Avg Build Cost | Gross Cap Rate |

|---|---|---|---|---|

| Bellevue | $3,100 | $2,800–$3,600 | $215,000 | 6.4% |

| Kirkland | $2,950 | $2,650–$3,300 | $205,000 | 6.5% |

| Redmond | $2,875 | $2,600–$3,200 | $200,000 | 6.6% |

| Seattle (Ballard/Wallingford) | $2,600 | $2,400–$2,950 | $185,000 | 6.4% |

| Seattle (Capitol Hill) | $2,725 | $2,500–$3,100 | $195,000 | 6.3% |

| Seattle (West Seattle/Beacon Hill) | $2,375 | $2,150–$2,700 | $180,000 | 6.1% |

| Seattle (Rainier Valley) | $2,150 | $1,950–$2,400 | $172,000 | 6.2% |

| Shoreline | $2,300 | $2,100–$2,600 | $178,000 | 6.0% |

| Bothell | $2,400 | $2,200–$2,700 | $182,000 | 6.1% |

| Renton | $2,250 | $2,050–$2,500 | $175,000 | 6.1% |

| Everett | $2,050 | $1,850–$2,300 | $168,000 | 5.9% |

| Tacoma (North End/Proctor) | $1,950 | $1,750–$2,200 | $152,000 | 6.6% |

| Tacoma (Stadium/6th Ave) | $1,850 | $1,650–$2,100 | $148,000 | 6.5% |

Gross cap rate is the headline; cash-on-cash return is the truth. After property tax, insurance, maintenance reserve (5%), vacancy (4%), and a $1,200/yr utility allowance, the rankings reshuffle hard.

Tacoma North End wins on cash-on-cash at 9.4% — lower entry price, lower property tax base, and minimal HOA-style overhead. Renton and Rainier Valley tie at 8.7%. Bellevue and Kirkland drop to 6.9% despite top-line rent — the build premium and King County assessed-value lift eat the margin. Capitol Hill posts 7.4% and is the only Seattle neighborhood where STR conversion still beats long-term net.

Seattle's 2026 STR ordinance caps non-primary-residence short-term rentals at 90 nights per year unless the operator holds an Operator's License and the unit is on the same lot as the host's primary residence. ADUs on the host's lot qualify — and that is the loophole most Puget Sound homeowners are using.

On our 40-unit sample, owner-occupied-lot STR ADUs in Ballard, Fremont, Capitol Hill, and downtown Bellevue grossed $58K–$74K/yr vs $30K–$36K long-term. After 22% in cleaning, 11% platform fees, 14% vacancy, and a furnished depreciation allowance, net STR income lands at $34K–$43K — only 1.05–1.15× long-term, with 4× the operating effort.

Bottom line for 2026: STR only outperforms long-term in three Puget Sound submarkets — downtown Bellevue, Capitol Hill, and Ballard near the locks — and only when the ADU is on the host's primary-residence lot. Everywhere else, long-term wins on net income and is 90% less work.

Bellevue (Crossroads, Bel-Red, Lake Hills) — Tech-corridor demand from Microsoft and Amazon Bellevue offices. Long-term wins; STR caps tighter than Seattle. Kirkland (Juanita, Rose Hill) — Premium waterfront-adjacent rents; furnished corporate rentals (3–6 month leases) outperform both standard long-term and pure STR. Redmond (Education Hill, Overlake) — Strong Microsoft commuter demand; 12-month leases fill in <14 days. Seattle Ballard/Wallingford — Highest STR upside in city; long-term still safer for first-time ADU landlords. Capitol Hill — Only Seattle neighborhood where STR net reliably beats long-term. West Seattle & Beacon Hill — Long-term only; tenant demand is families and remote workers, not travelers. Rainier Valley — Highest cap-rate Seattle submarket; rent-to-cost ratio leads the city. Tacoma North End & Proctor — Lowest entry price, highest cash-on-cash; long-term only — Tacoma's 2025 STR ordinance is the strictest in the Puget Sound.

Property: 720 sq ft DADU, Ballard, Seattle. Built 2025 for $185,000 turnkey. Owner financed $148K at 6.75% (30-yr).

Annual gross long-term rent: $31,200 ($2,600/mo). Property tax (Seattle/King County ADU lift): $1,850. Insurance: $720. Maintenance reserve (5%): $1,560. Vacancy reserve (4%): $1,250. Utility allowance: $1,200. Annual debt service: $11,520. Net cash flow after debt: $13,100/yr — a 8.85% cash-on-cash return on the $148K cash-out-refinance equity. Pre-debt NOI: $24,620, which is a 13.3% return on the $185K all-cash basis before any 2026 heat pump rebate stack (full rebate breakdown here).

How much rent can I get for a 700 sq ft ADU in Seattle in 2026? A 700 sq ft ADU in Seattle rents for a median of $2,600/month in 2026, with a typical range of $2,150 in Rainier Valley to $2,950 in Ballard and Capitol Hill.

What is the average ADU rental income in Bellevue in 2026? Median Bellevue ADU rent is $3,100/month in 2026, with corporate furnished rentals in Crossroads and Lake Hills pushing $3,600/month for 700 sq ft units.

What is the cap rate on a Puget Sound ADU in 2026? Median gross cap rate is 6.1% across the Puget Sound, with Tacoma North End and Redmond leading at 6.6% and Bellevue/Kirkland at 6.4–6.5%.

Is short-term rental (Airbnb) better than long-term for an ADU in Seattle? Only in Ballard, Fremont, Capitol Hill, and downtown Bellevue on owner-occupied lots. Seattle's 2026 STR ordinance caps non-primary units at 90 nights/year. Net STR income is 1.05–1.15× long-term in those neighborhoods only, with 4× the operating workload.

What is the cash-on-cash return on an ADU rental in Tacoma in 2026? 9.4% in North End and Proctor neighborhoods — the highest in the Puget Sound — driven by lower build cost ($148K–$152K) and lower property tax base.

Do I have to live on the property to rent out my ADU in Washington in 2026? No. HB 1337 (2023) eliminated owner-occupancy requirements for ADUs across Washington urban growth areas including Seattle, Bellevue, Kirkland, Redmond, Renton, Tacoma, and unincorporated King, Pierce, and Snohomish counties.

How long until an ADU pays itself off in Seattle in 2026? Median payback period is 7.2 years on a $185K Ballard DADU at $2,600/mo rent, including all rebates and the 25C federal tax credit.

What's the vacancy rate on Puget Sound ADUs in 2026? Average 14 days between tenants across our 40-unit sample — roughly 4% annualized vacancy, well below the 6.8% Puget Sound multifamily average.

Can I rent my ADU as a furnished corporate rental in Kirkland or Bellevue? Yes, and it outperforms both standard long-term and pure STR in those submarkets — 3–6 month corporate leases gross $3,400–$4,200/mo for 700 sq ft furnished units near Microsoft and Amazon Bellevue campuses.

Are ADU rentals affected by Washington's 2024 rent cap (HB 1217)? Yes — annual rent increases on existing tenants are capped at 7% + CPI (max 10%) statewide as of mid-2024. New tenancies and initial lease pricing are unaffected.

What's the best ADU rental strategy in Redmond in 2026? 12-month leases targeting Microsoft commuters. Vacancy fills in under 14 days at $2,875/mo median for 700 sq ft in Education Hill and Overlake.

Should I furnish my ADU rental? Furnished adds ~$300–$500/mo in Bellevue, Kirkland, and Capitol Hill but only $100–$150/mo in Tacoma and Rainier Valley. Skip furnishing in any submarket where the lift is under $250/mo — the depreciation and turnover cost eats the premium.

1. Confirm your submarket rent with our internal data, Zillow Rent Index, and Apartments.com — not Craigslist. 2. Pick your strategy by neighborhood: long-term default everywhere; corporate furnished for Kirkland/Redmond/Bellevue; STR only in Ballard, Capitol Hill, downtown Bellevue on owner-occupied lots. 3. Stack the 2026 heat pump rebate to lower your build basis by $7K–$13K before you ever rent the unit. 4. Model unit-lot subdivision if you may want to sell separately — see our sell-a-DADU-separately playbook. 5. Check our 2026 Seattle DADU boom analysis for full cost comparisons across DADU vs basement vs garage conversion.