2026 GUIDE • WASHINGTON DC

How much does an in-law suite permit cost in Washington DC in 2026

Most in-law suite permits in Washington DC cost $1,000 – $4,200 in 2026, with the total driven by declared construction value, whether the project creates a second kitchen or dwelling unit, and the District’s technology and enhancement surcharges.

An in-law suite — sometimes called an accessory dwelling unit, granny flat, or basement apartment — adds a self-contained living space with a bedroom, bath, and often a kitchenette. In DC, the key distinction is whether your project is treated as part of the primary dwelling or as a second dwelling unit, because that affects zoning review and the permit path.

Cost breakdown (2026)

Fee component	Typical 2026 cost
Filing fee	$32
Base permit fee (tiered by construction value)	$350 – $2,100
Plan review	$150 – $750
Electrical / mechanical / plumbing add-ons	$180 – $550
Technology fee (10%)	~10% of permit fee
Enhancement fee (6%)	~6% of permit fee
Zoning fee (ADU / two-unit, where applicable)	$50 – $150
Typical total	$1,000 – $4,200

In-law suites often pair with a basement or rear addition — see DC rear addition permit costs and DC rooming house permit costs for related scopes.

Also decide early whether you want a legally separate unit or simply an extension of your home. A separate unit usually needs its own entrance, kitchen, and utility arrangements, and it faces a stricter zoning review. An extension keeps you in a simpler, cheaper path if you do not need independent occupancy.

What affects the price

• Declared construction value. The primary driver. A modest basement bath-and-bedroom declares less than a full suite with kitchen, laundry, and separate entrance.
• Unit classification. If the work is reviewed as a separate dwelling unit, zoning review and a zoning fee typically follow.
• Egress and fire separation. Sleeping rooms, stair separation, and alarm coverage raise review depth.
• Historic district or HPRB review. Exterior changes such as a new entrance in a historic district may require Historic Preservation Review Board review.
• Utility separation. Separate meters or a new service for an independent unit add scope and trade permits.
• Expedited processing. Available for an added fee when your schedule is tight.

How the fee is calculated

DOB uses a formula under the DOB fee schedule (2026), not a flat residential rate:

1. Filing fee: roughly $32, charged up front.
2. Base permit fee: tiered by declared construction value — roughly $148 for the first $1,000 of value, then approximately $10 per additional $1,000. Minimum flat tiers for very low-value work run around $33 – $65.
3. 10% technology fee: added on top of the permit fee.
4. 6% enhancement fee: also added on top.
5. Zoning fee: where a zoning review applies.

The key takeaway: fees scale with declared construction value. A $50,000 basement suite and a $250,000 full accessory unit sit in very different fee tiers, and the percentage surcharges add proportionally on top.

Worked example: a $100,000 in-law suite lands near $1,138 in base fees before surcharges (about $148 plus roughly $990 in per-thousand charges). The 10% technology and 6% enhancement fees add roughly $182, and filing plus plan review bring the total toward the middle of the range.

Timeline & steps

1. Zoning and feasibility check. Confirm whether the project is a dwelling unit or an extension — 2 – 4 weeks.
2. Design. Egress, plumbing layout, and fire separation drawings — 3 – 6 weeks.
3. File via CitizenAccess. Submit to DOB through the CitizenAccess portal.
4. Plan review: typically 3 – 8 weeks for residential additions and conversions.
5. Permit issuance, construction, and inspections. Trades pull their own permits; final inspections close out the work.

Common mistakes

• Adding a second kitchen without checking zoning. The stove is often what reclassifies the project.
• Ignoring egress and fire separation. These are the most common review corrections in suite projects.
• Forgetting trade permits. New bath, kitchen, and HVAC work all require separate trade permits and fees.
• Building unpermitted. Unpermitted suites create resale and financing problems and often require costly retroactive permitting.

FAQ

Is an in-law suite the same as an ADU in DC?

They overlap. An in-law suite may be an extension of the primary dwelling or a separate accessory dwelling unit, depending on the design and zoning classification. The classification affects review.

Do I need a permit to add a basement in-law suite?

Yes. Any habitable-space conversion with new walls, egress, or utilities requires a construction permit.

Will a second kitchen trigger zoning review?

Often, because a second kitchen can signal a second dwelling unit. Confirm the zoning treatment before designing around it.

Are trade permits included in the total?

No. Electrical, mechanical, and plumbing permits are separate and are pulled by the licensed trade contractors.

How long does approval take?

Plan on 4 – 10 weeks from filing to permit, longer if a zoning review applies.

Disclaimer

Figures on this page are 2026 estimates based on the DC Department of Buildings fee schedule. Fee schedules change; always verify current amounts with DOB directly or through the CitizenAccess portal before filing. This article is informational and is not legal or financial advice.

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DC Permit Cost Calculator (2026)

Base $200 + $0.75/sqft. Expedite x2.5. DCRA Source 2026.

Last Updated: Sep 2026 | Sources: DCRA | Reviewed

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DC Permit Cost Calculator (2026)

Base $200 + $0.75/sqft. Expedite x2.5. DCRA Source 2026.

Last Updated: Sep 2026 | Sources: DCRA | Reviewed

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DC Permit Cost Calculator (2026)

Base $200 + $0.75/sqft. Expedite x2.5. DCRA Source 2026.

Last Updated: Sep 2026 | Sources: DCRA | Reviewed

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DC Permit Cost Calculator (2026)

Base $200 + $0.75/sqft. Expedite x2.5. DCRA Source 2026.

Last Updated: Sep 2026 | Sources: DCRA | Reviewed