Real Property is the sole authority responsible for maintaining the official Suffolk County Tax Map for ad valorem purposes. Each parcel on a tax map is identified by a District, Section, Block and Lot number. For instance, on your tax bill the DSBL numbers could be 0200 (District is Brookhaven); 001.00 (Section 1); 01.00 (Block 1); and 001.000 (Lot 1). The tax map number is the keystone to the description of all real property in SuffolkCounty. There are over 585,000 parcels in the County. The tax map parcel must exist prior to verification and recording of numerous documents.

The assemblage and apportionment of lots and the assignment of new tax map numbers to parcels are performed by this division. Typically, the application to do so is first filed with the assessor in the town or village where the property is located. It is in the town or village building and planning departments where you are best advised to check parcel zoning and variance requirements if you plan on splitting a lot, assembling lots, and/or erecting any structures or creating any other uses on the parcels.