The quickest way to find your block and lot number is to pull out your most recent property tax bill, where it’s printed near the top next to the property address. Every parcel of land in the United States carries a unique identifier assigned by the local assessor, and that identifier, whether your county labels it a block and lot, an Assessor’s Parcel Number, or something else, is the key to every public record tied to the property. If you don’t have a tax bill handy, your deed, title insurance policy, and county assessor’s website will all get you the same number.
What a Block and Lot Number Is
A block is a defined area of land, usually bounded by streets or natural features. Within each block, individual parcels get their own lot number. Together, the two numbers pinpoint exactly which piece of ground you own, and that combination stays constant even if the building is torn down, the property changes hands, or the street gets renamed.
The system comes from subdivision plats: official maps filed with the county when raw land is divided into buildable parcels. A typical lot-and-block legal description reads something like “Lot 2, Block 4, Oak Hills Estate, Johnson County, Kansas,” and that alone is enough to identify the property on a deed or in court.
In cities with multiple administrative districts, the identifier picks up an extra layer. New York City concatenates a borough code with the block and lot to form a Borough-Block-and-Lot, or BBL, so no two parcels across the five boroughs share the same number.1NYC Planning. Geosupport User Programming Guide – Chapter VI – Section 02 – Tax Lots and BBLs
Other Names You Might See
Not every county calls it a “block and lot number.” Depending on where you live, the same identifier may appear as an Assessor’s Parcel Number (APN), a Property Index Number (PIN), a Parcel Identification Number (PID), a Folio Number, a Tax Map Number, or a Property Account Number. If you call your assessor asking for your block and lot and they seem confused, ask for your parcel number instead.
One distinction is worth knowing. A lot number comes from a recorded subdivision or parcel map and reflects how the land was originally platted. An APN or PIN is assigned by the assessor for tax purposes and may not match the original plat exactly, especially if parcels have been split or combined over time. Both will get you to the same property record in practice, but the assessor’s number is what you need for tax lookups, and the lot-and-block description is what appears on deeds and title documents.
Where to Find Your Number
The fastest method depends on what you already have in hand. In rough order of convenience:
- Your property tax bill. The parcel number, block and lot, or APN is printed on every tax bill or assessment notice, usually near the top of the first page next to or just below the property address. If your mortgage servicer pays your taxes through escrow and you never see the bill, ask the servicer for a copy.
- Your deed. The recorded deed contains the full legal description, which includes the lot and block designation if the property is in a platted subdivision. You received a copy at closing, and the original is on file with the county recorder.
- Your title insurance policy. Schedule A of a title insurance commitment lists the legal description, typically as an attached exhibit showing the lot, block, and subdivision name.
- The county assessor’s website. Nearly every county offers a free online portal where you can search by street address and retrieve the parcel number, assessed value, tax history, and ownership details.
- County GIS maps. Many jurisdictions maintain interactive Geographic Information System maps that let you click directly on a parcel to see its identifier, boundaries, acreage, and zoning.
- An in-person visit. The county assessor, recorder, or clerk’s office can look up the information on internal systems. Some offices charge a small fee for certified copies.
Using the Assessor’s Website
County assessor sites are the workhorse tool. Enter the street address and the system returns a summary page showing the parcel number, current owner, assessed value, tax amounts, and often a link to the tax map. Some portals also accept searches by owner name or by the parcel number itself, useful when you’re researching a property you don’t yet own.
The search typically asks for the street number, street name, and either the city or zip code. You don’t usually need the full zip, but it helps when the same street name appears in multiple municipalities within one county. If the property was recently subdivided or the address was just assigned, the database might not recognize it yet; searching by the prior address or the owner’s name usually works.
Interactive GIS maps are worth a look even after you’ve found your number. They overlay parcel boundaries on satellite imagery, so you can see where your lot lines fall relative to fences, driveways, and neighboring structures. This is where many owners first notice that a fence sits two feet onto the neighbor’s property. GIS maps are prepared for assessment and reference, though, not as definitive boundary surveys, so treat them as a starting point rather than the last word on where your property ends.
Why the Number Matters
Street addresses are fine for mail, but they aren’t precise enough for legal purposes. An address can change when a city renumbers, and it doesn’t define the exact boundaries of the land. Deeds, mortgages, title insurance policies, tax liens, and zoning applications all rely on formal legal descriptions instead.
Lot-and-block descriptions are the most common in urban and suburban areas because most developed land has been subdivided at some point. A deed missing an adequate legal description, or carrying the wrong one, creates real problems: the property might not legally transfer to the buyer, boundary lines could be altered in the record, or improvements could be attributed to the wrong parcel. A street address alone isn’t considered legally sufficient, which is why the lot and block number (or another formal description) appears on every recorded instrument.
When the Number on Your Records Is Wrong
Errors happen more often than you’d expect, and the consequences run from mildly annoying to financially serious. A transposed digit in a lot number on a deed can mean you technically received title to your neighbor’s parcel instead of your own. A wrong block number on a tax assessment can mean you’re paying taxes on land you don’t own while the correct parcel goes untaxed. Neither problem fixes itself with time.
The fallout usually surfaces during a title search when someone tries to sell or refinance, and a gap in the chain of ownership turns up because a prior deed described the wrong parcel. The transaction stalls until the error is corrected, which can take weeks or months. If you’ve been paying taxes on the wrong parcel because of an assessor’s error, most jurisdictions have a formal claim process for recovering those payments, typically with filing deadlines and a requirement that you’ve already paid the tax before you can seek a refund.
How you fix the error depends on where it lives:
- A minor typo in a recorded deed, like a wrong lot number or misspelled subdivision name, can often be fixed with a corrective deed. It references the original recording information, identifies the specific error, and provides the correct language. Both the original grantor and grantee typically need to sign, and it gets recorded like the original.
- Some states allow the attorney or title professional who prepared the original deed to file a scrivener’s error affidavit identifying and correcting a minor clerical mistake. When properly executed, it relates back to the date of the original instrument. Not every state recognizes these, and the rules about who can sign vary.
- Errors on the tax roll or assessor’s map generally go straight to the county assessor, who has authority to correct clerical mistakes in property descriptions, names, and addresses. If the error affects your tax liability, a more formal process involving the appraisal review board or a written protest may apply.
- Major description errors, such as the wrong parcel being conveyed entirely, may require a new deed. In contested situations, a court action to quiet title may be the only remedy.
Catching mistakes early costs far less than unwinding them years later. Shortly after closing, compare the legal description on your deed against the assessor’s records and, if you have it, the original plat map. If anything doesn’t match, raise it with your title company while the transaction is still fresh.