What is a BBL, and why does it matter for your apartment?
A BBL is the Borough-Block-Lot number New York City uses to identify every tax lot. It is the key that ties your building's sales, permits, violations, and assessments together.
Updated Aug 18, 2026 · 5 min read
Almost every public record about a New York City property hangs off one identifier: the BBL. If you own an apartment and want to check what your building has sold for, what permits it has filed, or how it is assessed, the BBL is the key that makes those records line up.
What a BBL is
BBL stands for Borough, Block, and Lot. Together those three numbers identify a single tax lot - the parcel of land the city bills and records against. Written as one string it is ten digits.
| Part | Digits | Meaning |
|---|---|---|
| Borough | 1 | 1 Manhattan, 2 Bronx, 3 Brooklyn, 4 Queens, 5 Staten Island |
| Block | 5 | The tax block, padded with leading zeros |
| Lot | 4 | The lot within that block, padded with leading zeros |
So a Manhattan property on block 543, lot 21 has the BBL 1005430021: borough 1, block 00543, lot 0021.
Why it matters to you
The BBL is what lets otherwise unrelated city systems be joined together. Once you have it, you can pull:
- Recorded deeds and mortgages for the building, through ACRIS
- The Department of Finance assessment and tax history
- Department of Buildings permits and violations
- HPD housing violations, and 311 complaints tied to the address
- PLUTO land-use data: lot size, year built, unit counts, zoning
CurbScoop resolves listings to their BBL so that a listing, the building it sits in, and every recorded sale in that building appear as one connected picture rather than four disconnected searches.
Condos, co-ops, and the confusing part
Condominiums
In a condo, individual units generally receive their own billing BBL beneath the building's base lot, usually in a high lot-number range. Your unit sale is recorded as a deed against that unit BBL, which is why condo sale prices are visible in ACRIS.
Co-operatives
In a co-op the corporation owns the real property, and you own shares with a proprietary lease. The whole building shares a single BBL, and your apartment sale is a transfer of stock rather than a deed. That is why co-op prices are frequently missing from deed records, and why co-op valuation leans harder on listing data than on ACRIS.
How to find your BBL
- Look at your property tax bill or assessment notice - the BBL is printed on it.
- Search your address on CurbScoop; building pages are addressed by BBL.
- Use the city's ZoLa or ACRIS address search, which return the borough, block, and lot.
Once you have it, the next useful step is reading what those records say. See how to read an ACRIS record.
Common questions
- What does BBL stand for?
- Borough, Block, and Lot - the three numbers New York City uses to identify a tax lot. Written together they form a 10-digit identifier such as 1005430021.
- How do I find my BBL?
- Search your address on CurbScoop or on the city ACRIS and ZoLa tools. The BBL appears on your property tax bill and on every recorded document for the lot.
- Does my apartment have its own BBL?
- In a condominium each unit usually has its own billing BBL under the building. In a co-op the corporation owns the lot, so the whole building shares one BBL and individual apartment sales are recorded as stock transfers instead of deeds.