Navigating ALT and ALT CO Permits in NYC: What Property Owners Need to Know 

In the world of NYC construction and compliance, understanding the difference between an Alteration (ALT) permit and an Alteration with a Certificate of Occupancy change (ALT CO) is crucial. Whether you’re renovating a commercial space, expanding a building, or converting usage, these permits determine how your project is classified and what approvals you’ll need from the Department of Buildings (DOB). Filing under the wrong category can lead to delays, violations, and costly revisions—so getting it right the first time is key. 

What is an ALT Permit? 

An Alteration (ALT) permit is required for modifying an existing structure or space without changing its use, egress, or occupancy classification. Common ALT filings include: 

• Interior renovations that maintain the existing use (e.g., office upgrades, retail fit-outs, layout changes) 

• Structural repairs, including façade restorations and roof work 

• Mechanical and plumbing system upgrades 

Since an ALT permit does not alter the legal occupancy or use of a building, it does not require a new Certificate of Occupancy (CO). This means that businesses can often continue operations with minimal disruption during construction, provided all work remains compliant with DOB regulations. 

What is an ALT CO? 

An Alteration Certificate of Occupancy (ALT CO) permit is required when an alteration impacts the building’s use, occupancy, or egress. Examples of projects that require an ALT CO include: 

• Converting an office space into residential apartments 

• Increasing or decreasing the number of dwelling units in a building 

• Adding new exits, stairwells, or other major life safety upgrades 

• Changing the occupancy load of a space to a ‘Public Assembly’

Since these changes affect how the building is legally classified, an updated Certificate of Occupancy must be issued before the space can be occupied under its new use. 

Key Compliance Considerations for ALT and ALT CO Projects 

1. Zoning and Code Compliance 

ALT CO projects must comply with NYC Zoning Resolutions and Building Code regulations for their new use. Failing to account for zoning restrictions could result in rejected applications or major project redesigns. 

2. Temporary Certificate of Occupancy (TCO) 

For large-scale renovations that need partial occupancy before final approvals, a Temporary Certificate of Occupancy (TCO) may be issued. However, TCOs expire every 90 days and must be renewed until a final CO is obtained. 

How BVS Helps Expedite the Process

Navigating NYC’s complex permitting and compliance landscape can be overwhelming, but Building Violation Solutions (BVS) specializes in streamlining the process. Our team helps clients: 

• Determine whether an ALT or ALT CO permit is required 

• Expedite DOB approvals to avoid project delays 

• Resolve violations that could impact CO issuance 

If you’re planning an alteration or change in use, ensuring compliance from the start is essential. Contact BVS today to navigate the process with confidence and keep your project on track.