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NYC Department of Buildings · Owner guide
NYC DOB Alteration CO Work Permits (ALT-CO)
Alteration-CO (ALT-CO) is a DOB job type for qualifying alterations that affect building use, egress or occupancy; the work may require separate construction permits for specific work types. This category matters when an alteration changes the building’s occupancy arrangement or requires an amended Certificate of Occupancy. A property owner should confirm the job type with the Registered Design Professional (RDP) before planning individual trade permits.
Start with the DOB Permit Types and Certificates of Operation directory for the complete work-type list, or use the Department of Buildings Table of Content for wider NYC DOB subjects. Check the work scope and responsible applicant before treating an application as an issued authorization.
What Are Alteration-CO Work Permits?
Alteration-CO (ALT-CO) identifies a DOB job type for certain alterations that affect use, egress or occupancy. The approved job can require separate work permits for the actual construction activities.
DOB’s current guidance distinguishes Alteration-CO from ordinary Alteration and New Building applications. An incorrect initial job-type selection can require a new filing, so the occupancy decision should be made early.
Need help with Alteration-CO Work Permit coordination?
SLK Buildings can help property owners and project teams identify the correct DOB record, organize available project documents, and coordinate next steps with the responsible applicants, contractors and licensed professionals.
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When Does This DOB Authorization Apply?
Deciding whether this authorization applies requires a property-specific review of the proposed work, the existing conditions and the current agency records. In particular, compare current Certificate of Occupancy or occupancy records, along with existing and proposed use, exit and occupancy plans.
The first decision in an Alteration-CO project is whether the proposed use, exits, or occupancy arrangement actually changes. Compare existing occupancy documents with the proposed floor plans, not only the contractor’s description of the renovation. A project may involve partitions, structural changes, new mechanical equipment, plumbing, or several trades. The job type addresses the occupancy-related application, while the permits authorize particular construction activities. Checking those scopes separately helps owners understand why approval of the main filing does not authorize every contractor to begin work.
Work Type, Agency and Permit Boundaries
Owners reviewing Alteration CO work permits should understand that ALT-CO is a DOB job type, not one construction permit covering every trade. A project can involve General Construction (GC), Structural (ST), Mechanical Systems (MS) and other authorized work types under the related job.
DOB NOW: Build is the standard current filing platform for this subject. The authorized filer and contractor roles depend on the regulated work, and separate agency permissions may still be necessary.
An Alteration-CO project can involve more than one work type, even when the proposed construction appears to be a single renovation. DOB allows General Construction (GC) to be combine-filed with certain work types, including Structural (ST), Foundation (FO), Earthwork (EA), and Mechanical Systems (MS). Plumbing (PL) follows a different filing arrangement and cannot be combine-filed with GC. Owners should ask the Registered Design Professional which scopes belong in the initial filing and which require separate or subsequent applications. When reviewing Alteration-CO work permits, check the application status and issued permit for each work type, not only the overall job number. This helps avoid scheduling construction activities before the necessary authorization is in place.
Steps to Request or Review the DOB Authorization
Use the following sequence to avoid applying against the wrong property record or work scope:
- Confirm the building address, Building Identification Number (BIN), and existing job or equipment record. Check whether the project is new work or an older open job.
- Define the exact work or certificate need with the authorized professional. Compare the project details with the DOB work type and any separate trade or agency approvals.
- The RDP selects the appropriate Alteration-CO job type and coordinates the needed drawings and work types in DOB NOW: Build. Eligible contractors then request their corresponding permits after required approvals and pre-permit conditions.
- Review the submitted filing and DOB status. Address objections, missing documents, required attestations and pre-permit conditions through the authorized applicant.
- Confirm the issued permit or certificate and the approved work limitations before acting. Save the final record and track inspection or completion duties.
Documents and Information to Prepare
The responsible applicant should assemble project-specific information before starting the filing or records review:
- Current Certificate of Occupancy or occupancy records.
- Existing and proposed use, exit and occupancy plans.
- Design-professional work-type schedule and trade scopes.
- Approved job filing number and associated work-permit statuses.
DOB Review, Inspections and Closeout
When checking Alteration CO work permits, verify each associated issued permit, required inspection, and final occupancy step. Approval of the main job does not automatically mean that each trade is permitted or that a new Certificate of Occupancy has been issued.
An application marked approved, a permit issued and a project signed off are different milestones. Review the applicable status in DOB NOW or BIS, and retain supporting inspection and closeout documentation for the property record.
Before scheduling contractors, prepare a work-type register showing the related GC, ST, MS, PL, or other filings and their individual permit statuses. Link each permit to its responsible holder and the applicable drawings. If DOB requests revisions, identify which associated work types are affected and whether an amendment is needed. Near completion, track the inspections and sign-offs required for each trade alongside the Certificate of Occupancy process. The final occupancy document should never be treated as automatic merely because the building work appears finished.
Common Problems to Avoid
Treating ALT-CO as one permit
Match each trade and work activity to its own required work permit.
Missing an occupancy issue
Check whether changed use, egress or occupancy requires Alteration-CO treatment.
Closing the wrong work type
Track associated GC, ST, MS and specialty permit conditions separately.
How SLK Buildings May Assist
SLK Buildings may assist with Alteration-CO Work Permit coordination by reviewing available DOB records, organizing project information and identifying which applicant, licensed contractor or agency contact needs to handle the next action.
The authorized design and trade professionals remain responsible for regulated submissions and work, and DOB controls permit decisions, inspections and completion. Owners can begin by gathering the property address, existing filing numbers and a clear description of the proposed work.
Frequently Asked Questions
Is ALT-CO itself a construction permit?
No. It is a DOB job type; related construction work generally needs the applicable issued work permits.
Can an ALT-CO filing include GC and ST work?
Those work types may be associated with the job, subject to DOB filing and permit rules.
Is a new Certificate of Occupancy automatic?
No. DOB must accept the relevant completion and occupancy requirements before issuance.
Seeking Professional Guidance on NYC DOB Permits and Certificates
Property owners and project teams may need to confirm which DOB authorization applies, distinguish historical permits from current work types, and organize existing drawings, job numbers and approved records. When permits, certificates or multiple trades are involved, the responsible professionals and DOB must determine the permitted scope and required approvals.
SLK Buildings Assists with NYC DOB Permit Coordination
SLK Buildings may help identify the agency process, organize available records, coordinate with owners, contractors and licensed design professionals, and track outstanding requests within an agreed scope. For a project-specific discussion, provide the property address, known job or permit numbers, existing approvals and the work being proposed.
SLK Buildings is an independent consulting and construction-management firm, not affiliated with NYC DOB or any government agency. Information is for general education and is not legal, architectural, engineering or other licensed-professional advice. Qualified providers must perform regulated services. DOB and other agencies control official determinations, and SLK does not guarantee permits, certificates, inspections, approvals or outcomes.