A City of Bellingham ADU pays a land-use fee ($294 Type I or $728 Type II, effective 2026-10-01), a valuation-based building permit plus 65% plan review, a $1,470.93 park impact fee, a transportation impact fee reduced by a 50% ADU credit, and water ($2,911), sewer ($7,637) and stormwater ($364) system development charges.
Those fixed-dollar charges add up to $12,676.93 on a Type I path before the building permit is calculated. Every figure on this page comes from the City Building Permit Fee Worksheet BSD#064, dated 2026-08-27, and was last verified 2026-10-05. This page covers the City of Bellingham only. Unincorporated Whatcom County uses a different fee schedule.
Correction: ADUs Do Pay Impact Fees in Bellingham
Earlier pages on this site said ADU impact fees were $0 and that there were “currently none for ADUs in Whatcom County.” That was wrong, and this page supersedes those statements. Under the City Building Permit Fee Worksheet BSD#064 (2026-08-27), each ADU in the City of Bellingham pays a park impact fee of $1,470.93, and the transportation impact fee is reduced by a 50% ADU credit — not waived. Only the school impact fee is listed as not applicable.
The Complete 2026 Fee Schedule
One row per charge. The “Source” column names the document each figure comes from. Where a figure is not in our verified extract, the row says so instead of estimating it.
| Charge | Amount | Basis | Source |
|---|---|---|---|
| Land use ADU land-use review — Type I | $294 | Effective 2026-10-01. Was $214 before that date. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Land use ADU land-use review — Type II | $728 | Effective 2026-10-01. Was $531 before that date. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Building Building permit — new living space | $177.63/sf valuation | The permit fee is calculated from project valuation. This is the valuation rate per square foot, not the fee itself. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Building Building permit — garage-to-living conversion | $105.84/sf valuation | Valuation rate for converting garage space to living space. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Building Building permit — basement conversion | $146.13/sf valuation | Valuation rate for converting basement space. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Building Plan review | 65% of permit fee | Charged in addition to the building permit fee. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Trade permits Mechanical, plumbing and electrical permits | Not itemised here | Separate trade permits apply. Amounts were not part of our verified extract — confirm with the City Permit Center. | Pending verification |
| System development charges Water SDC | $2,911 | 5/8″ × 3/4″ meter. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| System development charges Sewer SDC | $7,637 | Single-family residential (SFR) rate. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| System development charges Stormwater SDC | $364 | CPI-adjusted. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Impact fees Park impact fee | $1,470.93 per ADU | Applies to each ADU. Exemptions are possible under BMC 19.04. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Impact fees Transportation impact fee | 50% ADU credit | Reduced, not waived. The ADU pays the remaining half of the applicable fee. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
| Impact fees School impact fee | N/A | Listed as not applicable to ADUs. | City Building Permit Fee Worksheet BSD#064 (2026-08-27) |
Source: City of Bellingham Building Permit Fee Worksheet BSD#064, dated 2026-08-27. Land-use fees reflect the increase effective 2026-10-01. Last verified 2026-10-05.
How the Building Permit Fee Is Calculated
The building permit is the one charge that changes with the size of the ADU. The City does not charge a flat building permit fee. It first sets a valuation for the project — the floor area multiplied by a per-square-foot rate — and then calculates the permit fee from that valuation. Plan review is then charged at 65% of the permit fee.
The valuation rate depends on what kind of space you are creating. New living space is valued at $177.63/sf, a basement conversion at $146.13/sf and a garage-to-living conversion at $105.84/sf. Converting existing space therefore produces a lower valuation, and a lower valuation-based fee, than building the same area new. The table below shows the valuation for a 600 sf ADU of each type.
| 600 sf ADU type | Valuation rate | Project valuation |
|---|---|---|
| New living space | $177.63/sf | $106,578.00 |
| Basement conversion | $146.13/sf | $87,678.00 |
| Garage-to-living conversion | $105.84/sf | $63,504.00 |
Valuation rates: City Building Permit Fee Worksheet BSD#064 (2026-08-27). Valuation is the basis for the fee, not the fee. Last verified 2026-10-05.
A detached garage conversion carries a second advantage. Under BMC 20.10.036(B)(15), as amended by Ordinance 2025-12-035 (effective 2025-12-23), an existing detached garage may convert to a detached ADU even where it does not meet current setback or lot-coverage standards, and no replacement parking is required. Current building, egress, fire-separation and energy code still apply.
Impact Fees: What Applies and What Does Not
Park Impact Fee
$1,470.93
Charged per ADU. Two ADUs on one lot pay it twice. Exemptions are possible under BMC 19.04 — ask before you pay.
Transportation Impact Fee
50% credit
ADUs receive a 50% credit. The fee is reduced, not waived. A City update to this fee is pending, so confirm the base amount at application.
School Impact Fee
N/A
The City fee worksheet lists no school impact fee for ADUs.
Source: City Building Permit Fee Worksheet BSD#064, dated 2026-08-27. Last verified 2026-10-05.
System Development Charges
System development charges (SDCs) pay for capacity in the City's water, sewer and stormwater systems. They are the largest fixed-dollar items on an ADU's City bill. The fee worksheet lists a water SDC of $2,911 for a 5/8″ × 3/4″ meter, a sewer SDC of $7,637 at the single-family residential rate, and a stormwater SDC of $364, which is CPI-adjusted.
SDCs are not the same as the physical cost of connecting. Running the sewer line, setting a meter and trenching are construction costs billed by your contractor. As of 2026-10-05, we estimate a City sewer hookup at $3,000–$8,000 (ESTIMATED), or $8,000–$21,000 all-in once general facility charges are included, and trenching at $15–$45 per linear foot (ESTIMATED). Our ADU permit and utility connection cost guide breaks those down further.
Worked Totals for Three ADU Sizes
These examples apply the 2026 schedule to a new detached ADU at 400, 700 and 1,000 sf — 1,000 sf is the City maximum per ADU under BMC 20.10.036, as amended by Ordinance 2025-12-035 (effective 2025-12-23). The fixed-dollar charges do not change with size. The valuation does, and the building permit fee and plan review are calculated from it.
| Example | Project valuation ($177.63/sf) | Fixed charges, Type I | Fixed charges, Type II |
|---|---|---|---|
| 400 sf new detached ADU | $71,052.00 | $12,676.93 | $13,110.93 |
| 700 sf new detached ADU | $124,341.00 | $12,676.93 | $13,110.93 |
| 1,000 sf new detached ADU | $177,630.00 | $12,676.93 | $13,110.93 |
Fixed charges = land-use fee ($294 Type I or $728 Type II) + park impact fee ($1,470.93) + water SDC ($2,911) + sewer SDC ($7,637) + stormwater SDC ($364). Add to each total: the building permit fee calculated from the valuation shown, plan review at 65% of that fee, trade permits, and the transportation impact fee after its 50% ADU credit. Source: City Building Permit Fee Worksheet BSD#064 (2026-08-27). Last verified 2026-10-05.
Two ADUs on one lot are allowed in the City of Bellingham. Each ADU pays its own park impact fee. Whether the second ADU also pays separate SDCs depends on how it is metered and connected, which the City confirms at application. For how these fees fit into a full build budget, see our ADU construction cost guide for Bellingham and Whatcom County.
Get a Fee Estimate for Your Lot
The fixed charges are the same for everyone. The building permit, plan review, trade permits, transportation fee and connection costs depend on your plan and your lot. Send us the basics and we'll put real numbers against each line.
Get a Fee EstimateThe October 2026 Land-Use Fee Increase
The City raised both ADU land-use fees effective 2026-10-01. The Type I fee went from $214 to $294 and the Type II fee from $531 to $728. The increase is small next to the SDCs, but it changes the fixed total: a Type I application now carries $12,676.93 in fixed charges, and a Type II application $13,110.93.
If you started an application before 2026-10-01, confirm with the City Permit Center which fee applies to it.
What This Schedule Does Not Cover
Unincorporated Whatcom County. Parcels outside city limits pay under the county's 2025–2026 Unified Fee Schedule (Ordinance 2024-063), which is in force through 2026-12-31. The county permit path is different too: a rural ADU outside a UGA needs an Administrative Approval Use (ADM), a Type II process under WCC 22.05.028, before the building permit. None of the City figures above apply there. Our side-by-side ADU rules reference table sets out the City and county standards in one place.
Design, engineering and construction. Permit fees are a small share of an ADU budget. A full ADU runs $450–$650/sq ft all-in as of 2026-10-05 — that figure already includes permitting. Finish level is what moves you within the band: builder-grade sits near $450/sq ft, premium near $650. See the full cost breakdown.
Lake Whatcom. If your lot is in the Lake Whatcom Reservoir overlay, BMC 16.80 bars new ADUs apart from narrow legacy exceptions. No fee schedule matters until that question is answered.
Frequently Asked Questions
How much are ADU permit fees in Bellingham?
In the City of Bellingham, the fixed-dollar charges for one ADU total $12,676.93 on a Type I land-use path or $13,110.93 on a Type II path: the land-use fee ($294 or $728 from 2026-10-01), a $1,470.93 park impact fee, and water ($2,911), sewer ($7,637) and stormwater ($364) system development charges. The valuation-based building permit, 65% plan review, trade permits and the transportation impact fee (reduced by a 50% ADU credit) are added on top. Source: City Building Permit Fee Worksheet BSD#064, dated 2026-08-27.
Do ADUs pay impact fees in Bellingham?
Yes. Each ADU in the City of Bellingham pays a park impact fee of $1,470.93, with exemptions possible under BMC 19.04. The transportation impact fee receives a 50% ADU credit, so it is reduced, not waived. No school impact fee applies. Source: City Building Permit Fee Worksheet BSD#064, dated 2026-08-27.
Is the transportation impact fee waived for ADUs?
No. The City of Bellingham applies a 50% credit to the transportation impact fee for ADUs. The ADU still pays the remaining half. An update to the transportation impact fee is pending at the City, so confirm the current base amount when you apply. Source: City Building Permit Fee Worksheet BSD#064, dated 2026-08-27.
Did Bellingham ADU land-use fees go up in 2026?
Yes. Effective 2026-10-01, the ADU Type I land-use fee rose from $214 to $294 and the Type II fee rose from $531 to $728. Source: City Building Permit Fee Worksheet BSD#064, dated 2026-08-27.
How is the Bellingham building permit fee for an ADU calculated?
The City calculates the building permit fee from project valuation. Valuation is the floor area multiplied by the City rate: $177.63/sf for new living space, $105.84/sf for a garage-to-living conversion and $146.13/sf for a basement conversion. Plan review is charged at 65% of the permit fee. Source: City Building Permit Fee Worksheet BSD#064, dated 2026-08-27.
Last verified: October 5, 2026. Fee source: City of Bellingham Building Permit Fee Worksheet BSD#064, dated 2026-08-27. Fees change; confirm with the City Permit Center before you budget.
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