NYC ADU Application: Complete Guide to Filing with DOB NOW

so you've checked your eligibility, picked a pre-approved plan, and maybe even lined up financing. now comes the part that trips up most homeowners: actually filing the ADU application with the NYC Department of Buildings through DOB NOW.

this guide walks you through every step of the DOB NOW filing process for ADUs, based on the current requirements under Local Law 127 of 2024 and the latest DOB NOW build release notes updated in february 2026.

before you file: what you need ready

do not log into DOB NOW until you have these items assembled. missing documents are the number one cause of application rejections and delays.

required documents

document	who provides it	estimated cost
architectural plans (or PAPL pre-approved plan)	licensed architect or PAPL library	$0 (PAPL) to $15,000-$40,000 (custom)
property survey	licensed land surveyor	$2,000-$5,000
DEP sewer availability letter	NYC DEP	~$500 filing fee
structural engineering report	licensed professional engineer	$3,000-$8,000
energy code compliance (ComCheck)	architect or energy consultant	included in design fees
geotechnical report (for new foundations)	geotechnical engineer	$3,000-$6,000
flood zone documentation (if applicable)	FEMA / DEP	varies

who can file

ADU applications must be filed by a registered design professional -- either a licensed architect (RA) or professional engineer (PE) registered with NYC DOB. homeowners cannot self-file. your architect or engineer will be the "applicant of record" on the filing.

if you need help finding a qualified professional, check our contractor and architect directory.

step 1: create an NYC.ID account

if you don't already have one, go to DOB NOW: Build and create an NYC.ID. this is the same login used for other city services. your design professional will likely already have one, but as the homeowner, you'll want your own account to track the application status.

step 2: create the right job type

this is where many applications go wrong from the start. you need to select the correct job type based on what you're building:

ADU type	DOB NOW job type	when to use
basement/cellar conversion	Alt-CO-GC (alteration with change of occupancy, general contractor)	converting existing space to a dwelling unit
garage conversion	Alt-CO-GC	converting an existing garage to living space
attic conversion	Alt-CO-GC	converting attic in a one-family home
new backyard cottage	New Building-GC (new building, general contractor)	constructing a new detached structure

critical mistake to avoid: do not file a regular alteration (Alt-GC) for ADU work that changes the occupancy or adds a dwelling unit. you need the CO (certificate of occupancy) variant because you're creating a new residential unit.

step 3: complete the PW1 application

once you've created the job, navigate to the PW1: Plan/Work Application tab. this is the main application form. here's what the ADU-specific fields look like:

the ADU section

under Filing Review Type > Work Type/Filing Includes, you'll see a new field: "Does the scope of work include an Ancillary Dwelling Unit?"

select Yes. this triggers additional required fields:

• pre-approved plan number -- if you're using a PAPL design, enter the plan number here. if you're filing a custom design, leave this blank or select "custom design."
• ADU location -- specify where the ADU is located on the property: basement, cellar, attic, attached structure, detached structure, or garage.
• main entrance location -- indicate where the ADU's separate entrance directly opens to (street, yard, common hallway, etc.). remember: a separate entrance is mandatory for all ADUs.

occupancy schedule update

you must update the building's occupancy schedule to include the new unit. the ADU should be designated as an Ancillary Dwelling Unit under Occupancy Group R-2 or R-3, depending on the building configuration:

• R-3: one- and two-family dwellings (most common for ADUs that keep the building at 2 or fewer units with the owner in the primary dwelling)
• R-2: may apply if the ADU creates a third unit in a two-family home without adequate fire separation

important: adding an ADU to a two-family home can technically create a three-family structure. if the ADU is in the basement, cellar, or attic and is not separated by a fire wall, the building becomes subject to state Multiple Dwelling Law. this changes your code requirements significantly. discuss this with your architect before filing.

step 4: upload required documents

DOB NOW requires all supporting documents to be uploaded digitally. typical uploads include:

• signed and sealed architectural plans (PDF format)
• structural calculations
• energy code compliance documentation
• property survey
• DEP sewer certification letter
• geotechnical report (for new construction)
• fire protection plans (if required for your building type)
• site safety plan (for certain construction types)

step 5: pay filing fees

DOB filing fees vary by work type and project value. typical ADU filing fees range from $500 to $2,500, depending on the scope. new construction (backyard cottages) tends to have higher fees than conversion projects. payment is processed directly through DOB NOW.

step 6: DOB plan examination

after submission, your application enters the plan examination queue. here's what to expect:

• pre-approved plan (PAPL) filings: significantly faster review since the design has already been generically approved. DOB primarily checks site-specific conditions.
• custom design filings: full plan examination for zoning, building code, fire code, and accessibility compliance. expect 4-12 weeks for initial review.
• objections: if the examiner finds issues, you'll receive objections through DOB NOW. your architect must respond to each objection and resubmit. this back-and-forth can add weeks or months.

the 7 most common DOB NOW filing mistakes

we see these errors constantly. avoid them and you'll save weeks of delays:

1. wrong job type. filing Alt-GC instead of Alt-CO-GC for conversions.
2. missing the ADU checkbox. if you don't flag the work as including an ADU, the application will be rejected.
3. no DEP sewer letter. this is required before filing and takes 2-4 weeks to obtain. start early.
4. incorrect occupancy classification. misclassifying R-2 vs R-3 triggers objections.
5. forgetting the separate entrance. every ADU must have its own entrance. if your plans don't show one, expect an objection.
6. filing in a restricted zone without realizing it. special districts like Bay Ridge have backyard ADU restrictions. check your eligibility first.
7. unsigned or unsealed plans. all drawings must be signed and sealed by the registered design professional. digital signatures are accepted.

after approval: what happens next

once DOB approves your plans, you'll receive a work permit. from there:

1. hire a licensed general contractor (or use our directory)
2. pull the permit and post it at the job site
3. schedule DOB inspections at required milestones (foundation, framing, electrical, plumbing, final)
4. pass final inspection and receive your Certificate of Occupancy

without the CO, you cannot legally occupy or rent the ADU unit. don't skip this step -- it protects you legally and financially.

how nycadu.com helps with the filing process

the DOB NOW filing is just one piece of the puzzle. here's how our tools support you through the full permit process:

• eligibility checker -- verify your property qualifies before spending money on an architect
• pre-approved plan reviews -- understand the pros and cons of each PAPL design
• document checklist -- track every document you need for filing
• architect and contractor matching -- find professionals who specialize in ADU filings

ready to start? check your eligibility first, then use our document checklist to get organized before you file.