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Can I subdivide my lot in Seattle? What the 2026 rules allow

15 min read · 10 sections · Published October 15, 2026 · Updated October 20, 2026
By Henos Adhana · Licensed WA Real Estate Broker #25016434 · eXp Realty

You can split a house lot into separate lots only if each new lot can be at least 5,000 square feet, the minimum in Seattle's Neighborhood Residential zone since January 21, 2026. For two lots that usually means about 10,000 square feet, not counting wetlands, creek corridors or protected steep slopes. A short plat creates up to nine lots, with city review fees from $5,510 and several months of review. A smaller lot can still hold several homes, each sold on its own unit lot.

What a short plat is#

Short plat: Splitting one lot into new lots, each at least 5,000 sq ft in Seattle. A drawing of a lot split down the middle by a dashed line into two lots of 5,000 square feet, a house on each.
Each new lot has to meet the 5,000 square foot minimum on its own.

Start with the numbers: your zone and 5,000 square feet#

Seattle rewrote its Neighborhood Residential zone to meet the state's middle housing law. The new rules, Ordinance 127376, took effect on January 21, 2026, and for subdividing, one line decides most cases: a new lot must be at least 5,000 square feet.

Creek corridors, wetlands and their buffers, shoreline setbacks and the protected parts of steep slopes do not count toward that figure. So a two-lot split needs roughly 10,000 square feet that counts, and each lot still has to work on its own.

Worked for three lots. A flat 10,000 square foot corner lot can, on paper, become two 5,000 square foot lots, each on a street. A 7,500 square foot lot cannot make a second lot, but the zone's density limit, one home per 1,250 square feet, allows six homes on it, which can be sold one at a time on unit lots. A 12,000 square foot lot with a ravine along the back may count for far less than 12,000.

*Check whether it is already two lots. Some parcels combine two or more lots from the original plat, as the legal description will show. Before 1972 owners could also split lots by deed; since then it has taken a platting action. SDCI, the city's permit department, will say whether a parcel is a separate building site in a legal building site letter, from two hours at the land use rate ($1,102).

Confirm your zone on the city's GIS map. A second rezoning bill, for neighborhood centers and transit corridors (Council Bill 121173), was still in committee on October 20, 2026. The city's Planning Commission expects the Council to take it up in early 2027. On September 9, 2026 a state hearings board found the city's environmental study for the plan inadequate. The city says the zoning stays in effect while it redoes the study.

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Not sure whether to fix it or price it in?

Find out what it would actually sell for

Four ways to divide land, and what each is for#

Seattle has four platting tools. Pick by what you want to end up with.

Lot boundary adjustment. Moves the line between existing lots without creating a new one, and every lot must still meet the zone's minimums. It's how you sell a strip of yard to a neighbor, and SDCI decides it with no public notice or appeal.

Short subdivision, or short plat. Creates two to nine separate building lots. State law defines a short subdivision as four or fewer lots and lets cities raise that to nine, as Seattle has. It includes public notice, a comment period, SDCI's decision and a right of appeal.

Full subdivision. Ten or more lots, decided by the city's Hearing Examiner after a public hearing.

Unit lot subdivision. Divides a specific housing project, permitted or built, so each home can be sold on its own unit lot. Up to nine unit lots use the short plat process. Unit lots are not separate building sites and have no minimum size.

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Unit lots: selling homes you build, not land#

Unit lots are a common way to sell new Seattle townhouses, and now that a Neighborhood Residential lot can hold four or more homes, they work on an ordinary house lot too. The building permit application comes first, and the plat is recorded only once the homes exist or their permit is ready to issue.

Each buyer gets less than a full lot. The plat must note that a unit lot is not a separate buildable lot and that later building may be limited by the standards applied to the whole parent lot. Shared driveways, parking and open space run on recorded easements and joint use and maintenance agreements. How that reads to a buyer.

*An ADU cannot go on its own unit lot. The code bars separating an accessory dwelling unit from its main house by unit lot subdivision. An ADU can still be sold as a condominium unit. A backyard home permitted as a principal unit rather than an ADU appears to be allowed on its own unit lot, but no city page says so in those words, so confirm with SDCI before you rely on it.

State law is still moving. Washington first required cities to offer unit lot subdivisions in 2023 (SB 5258, chapter 337, Laws of 2023, effective July 23, 2023), now RCW 58.17.060(3). SB 5559, effective July 27, 2025, added required plat notes, clear and objective standards, no hearing before the decision, notice to owners within 250 feet, and notice to buyers of a unit lot's legal status. Seattle has until July 27, 2027 to adopt those procedures.

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What the site has to pass: access, utilities, drainage, trees and slopes#

Access. Each new lot needs at least 10 feet on a street or on a recorded access easement at least 10 feet wide. No lot can be under 10 feet wide for more than 10 feet or have more than six sides, and where an improved alley runs behind, new lots generally must use it.

Water and sewer. Every plat needs a free availability certificate from Seattle Public Utilities, which SDCI requests and which usually takes about 20 business days; it flags any main extension. A side sewer crossing another lot needs a recorded easement, a shared one needs a recorded joint use and maintenance agreement, and with no public sewer in an abutting street or alley you may have to extend the main. Start with the side sewer card.

Drainage. Every short plat, unit lot subdivision and boundary adjustment gets a preliminary drainage review under the Stormwater Code, updated July 1, 2026. For a short plat in this zone, it assumes each lot is built out to its maximum lot coverage plus driveways and walks, and applies the standards for the whole property's size, not each lot's.

Trees. A short plat must be designed to keep as many existing trees as it can, and the application shows every tree 6 inches or more in diameter. Under the tree code in force since July 30, 2023, trees 24 inches or more come out for development only in limited cases, such as blocking the allowed lot coverage or required access, and removed trees of 12 inches or more must be replaced. One large tree can decide where the line goes.

Steep slopes and other critical areas. Seattle treats slopes of 40% or more, over at least 10 feet of rise, as steep slopes. With one of those, a wetland or a creek corridor on the site, every new lot needs a building area and access outside the critical area and its buffer, plus a topographic survey, a geotechnical report and an environmental checklist.

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How a short plat runs, start to finish#

SDCI's sequence from its Tips, with the time limits in the city's code. A unit lot subdivision follows the same path after its building permit application.

  1. Check the lot firstConfirm the zone, lot size and critical areas on the city's GIS map, pull the side sewer card and note large trees. SDCI offers 20 minutes of free video coaching; a paid land use coaching hour costs $551.
  2. Hire a licensed land surveyorA Washington licensed surveyor prepares the survey, which goes in stamped with the application and shows lot lines, buildings, easements, utilities and trees.
  3. Start the preliminary applicationApply through the Seattle Services Portal. Most projects get a $219 site visit and a preliminary report where City Light, utility, drainage and transportation reviewers flag problems, including street improvements.
  4. Submit at an intake appointmentFees are due at intake, including King County's recording fee, which is refunded if the plat is not approved.
  5. Notice and commentSDCI posts a land use sign and has up to 28 days to accept the application as complete, then 14 days to publish a notice and mail one to properties within 300 feet. Comments run 14 days, extendable by 14 on a written request.
  6. Review and decisionReviewers send corrections, and each needs an answer. SDCI has 120 days from a complete application to decide, 170 with environmental review or a special exception, not counting time you spend on corrections.
  7. The appeal windowAnyone can appeal to the Hearing Examiner within 14 days after the decision is published, which means a public hearing.
  8. Record the platOnce the conditions are met, the plat is recorded with King County and SDCI issues the permit. The lots are final at recording, not at the decision.

Rules, programs and costs change, and they differ between Seattle and each surrounding city. Figures on this page are dated where they appear. Confirm anything specific with the relevant city or agency before you rely on it.

What the city and county charge, worked for a two-lot short plat#

The 2026 minimums from Seattle's Fee Subtitle for a simple two-lot short plat with no critical areas. SDCI bills each land use review hour past ten at $551, the rate since January 1, 2026, and drainage, geotechnical and building review at $292 an hour.

Minimum city and county fees · two-lot short plat, 2026
FeeAmount
Land use review, first 10 hours10 hours at $551. A unit lot subdivision has the same minimum$5,510
Pre-application site visitThree quarters of an hour at $292. Most projects need one$219
Intake appointmentCharged for each intake$292
Public notice$292 for the bulletin notice, $180.75 for the land use sign and $292 for up to 500 mailed notices$764.75
Technology fee5% on every SDCI fee above$339.29
Recording the plat with King CountyFor the first 18 by 24 inch sheet, plus $5 for each additional sheet$423.50
Minimum before extra review hoursAbout $7,550$7,548.54

Private costs come on top. A licensed surveyor always, and depending on the site a civil engineer, an arborist, a geotechnical engineer and an attorney for the easements and maintenance agreements. Get written quotes for your lot before you commit.

A lot boundary adjustment starts at five review hours, $2,755. A pre-submittal conference is two hours, $1,102.

How long. SDCI says a short plat takes several months for review and a written decision. The city's own limits, 28 days to accept the application, 120 to decide and 14 for appeals, add up to 162 days of city time, before the survey, your correction rounds and recording.

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Often better than subdividing: build, add a unit, or sell to a builder#

Subdividing makes sense when you want to sell land and keep your house. Often one of these gets further, faster.

Build more homes on the lot you have. State law requires Seattle to allow at least four homes per residential lot, six within a quarter mile of a major transit stop or with two affordable, and Seattle allows one per 1,250 square feet where that is more. Sell them one at a time on unit lots, where the 5,000 square foot minimum does not apply.

Add one or two ADUs and keep the lot. Seattle allows two per lot, up to 1,000 square feet each, or 1,200 with three or more bedrooms, with no parking required. Can your lot take a backyard cottage?

Sell the whole lot to a builder. The builder takes on the survey, the fees, the months of review and the risk of a no, and prices that into the offer. Splitting first can be worth more if it works; selling whole is simpler and sooner. I would have the lot valued both ways before paying a surveyor.

Or wait for the lot split law. HB 1096 (chapter 301, Laws of 2025) requires cities to offer a staff-level split of one residential lot into two, with no public hearing or administrative appeal, by July 27, 2027 for Seattle. The city said it would bring legislation in 2026; I found no lot-split bill in the City Council's records as of October 20, 2026. Both lots must still meet the local minimum, so in Seattle it changes the process more than the math.

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Taxes, your mortgage and the paperwork#

Excise tax applies to every sale this produces: a new lot, a unit lot, or a strip sold to a neighbor. It is the seller's obligation, and at most Seattle prices it comes to about 1.6% to 1.7% of the price. The rates, worked to the dollar.

Tax on the gain is a question for an accountant. It can turn on how long you have owned the land, whether it is part of your home, and how the cost is divided between the lot you sell and the one you keep. Ask before you sign anything.

Your lender has a say. The mortgage covers the whole parcel, so selling part needs the lender's release. On a Fannie Mae loan, for example, the servicer reviews it on Form 236 and can require a paydown to hold the loan-to-value at the higher of where it was or 60%.

Plan the whole split at once. For five years after a short plat is recorded, dividing the land again past nine lots in total takes a full subdivision. In return, the new lots are treated as meeting the city's lot requirements for at least five years, unless the City Council finds circumstances have changed.

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Common questions#

Can I subdivide my lot in Seattle?

In the Neighborhood Residential zone, only if each new lot can be at least 5,000 square feet, not counting critical areas such as wetlands and protected steep slopes. That usually takes about 10,000 square feet for two lots, plus street or easement access, utilities, drainage and room to build around protected trees. On a smaller lot you can build more homes and sell each on a unit lot.

What is a short plat in Washington state?

The recorded map of a short subdivision. State law defines a short subdivision as dividing land into four or fewer lots for sale, lease or transfer, and lets a city raise the limit to nine. Seattle allows up to nine; ten or more is a full subdivision with a Hearing Examiner hearing.

What is the minimum lot size in Seattle?

For a new lot in the Neighborhood Residential zone, 5,000 square feet, since January 21, 2026. Unit lots have no minimum. Existing lots smaller than 5,000 square feet can still be built on, with up to four homes on most of them.

How much does it cost to short plat in Seattle?

The city's minimum is $5,510 for the first ten hours of land use review, then $551 an hour, plus intake, notice, a 5% technology fee and King County's $423.50 recording fee: about $7,550 at the minimums for a simple two-lot plat. The survey, engineering and any utility work come on top and need quotes.

How long does a short plat take in Seattle?

SDCI says several months for its review and a written decision. The city's own limits are up to 28 days to accept the application, 120 days to decide, not counting time spent on corrections, and 14 days for appeals. The survey beforehand and recording afterward add to that.

Can I sell part of my lot to my neighbor?

Yes, through a lot boundary adjustment, as long as no new lot is created and both lots still meet the zone's minimums. There is no public notice or appeal, the city's minimum review fee is $2,755, the sale is subject to excise tax, and if you have a mortgage your lender has to release that piece.

Can I sell my ADU or backyard cottage separately?

Not on its own unit lot. Seattle's code bars a unit lot subdivision that separates an ADU from its main house. An ADU can be sold as a condominium unit. A backyard home permitted as a principal unit rather than an ADU appears to be allowed on its own unit lot, but no city page says so in those words, so confirm with SDCI before you rely on it.

What is the 75/80 rule in Seattle?

It was an exception in the old code. A lot smaller than the zone minimum could still be created or built on if it was at least 75% of that minimum and at least 80% of the average lot on the same block. It went away on January 21, 2026. New lots now need 5,000 square feet with no averaging. A short plat application that was complete before that date is reviewed under the old rules (RCW 58.17.033).

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