Address Verification for Insurance Quote Forms
What insurance regulators say about pricing by location, which address fields a quote needs, and how autocomplete and verification fit into one form.
An address verification API for insurance checks the address on a quote or application against postal data and, when it finds a match, returns it in standard form with the county, ZIP+4 and unit. That matters because location is a rating factor. The NAIC tells consumers that a home's location affects what they pay, and Maryland's insurance regulator reports that 11 of the state's top 13 auto insurance groups define rating territories by ZIP codes or groups of ZIP codes.
Why the quote form needs a clean address
Here is what regulators themselves say about location and price. We quote them word for word, because each source speaks only for its own state or audience.
| Source | What it says | What it means for the form |
|---|---|---|
| NAIC, Regulatory Resources for Consumers on Personal Lines Pricing and Underwriting (2022), homeowners | "Your home's location affects what you pay for homeowners insurance." "Insurance companies consider how far you live from a fire station when they calculate your premium." | The property address has to point at the right building, so the location factors are looked up for the right place. |
| NAIC, same resource, auto | "It's important to tell your insurance company where you keep (or "garage") your vehicle. You may pay more or less based on where you live or keep your car." | The garaging address is a pricing input, so it needs the same care as the home address. |
| Maryland Insurance Administration, Report on Rate Assignment by ZIP Code (October 31, 2025) | Territorial rating assesses risk "based on the physical location where a vehicle is primarily parked overnight (i.e., the "garaging address")". "All of the top 13 insurance groups, which together comprise 95% of the PPA insurance market in Maryland, use territory as a rating factor. 11 of these 13 insurance groups define their territories in terms of ZIP codes or groupings of ZIP codes." (PPA means private passenger automobile.) | A wrong ZIP code can put an applicant in the wrong rating territory. |
| Texas Department of Insurance, Texas Windstorm Insurance Association (TWIA) Overview (October 1, 2026) | TWIA "provides windstorm and hail coverage in the following 14 "first-tier" Texas coastal counties" and, in Harris County, "for risks that are east of State Highway 146 and located in the city limits of certain specifically designated communities", namely "Pasadena, Morgan's Point, Shoreacres, Seabrook, and La Porte." | Whether a property is inside a program's coverage area can depend on the county, and sometimes on more than the county. |
The address fields that matter
| Field | Why a quote or underwriting step uses it |
|---|---|
| County | Some programs cover areas defined by county, like the TWIA coastal counties above. If your form does not ask for the county, it has to come back from the check. The county answers only the geographic question; it does not settle eligibility, inspection requirements or whether an insurer accepts the risk. |
| ZIP code and ZIP+4 | In Maryland, ZIP codes or groups of them define rating territories for 11 of the top 13 auto insurance groups. The ZIP+4 comes back even when the applicant typed only five digits: in both live checks below, the match code for the ZIP+4 is "Inferred", meaning it was filled in. |
| Unit number | In a building with apartments, the unit identifies which home is being insured. DPV code D (DPV means delivery point validation) means the building number is confirmed but the unit number is missing; S means the unit number given was not confirmed. Either is worth asking about on the form. |
| Record type | S street, H high-rise (a building with units), F firm, P PO box, R rural route. A PO box is a mailing address. It does not tell you where a home stands or where a car is parked overnight. |
| Private mailbox flag | The cmar field. Y means the address is a commercial mail receiving agency (a private mailbox store). Like a PO box, it is a place mail is received, so ask for the property or garaging address separately. |
| Deliverability status | Confirmed, ConfirmedPrimaryOnly (the building is confirmed, the unit is missing or not confirmed), NotDeliverable or Unknown. Use it to decide whether to accept the address, ask for the unit, or ask the applicant to check it. |
Not on this list: residential or commercial, vacancy, flood zone, ownership, building characteristics. sthan.io's verification response does not include residential or vacant flags, flood zones, ownership or building characteristics (the full field list is in the API docs). Obtain those separately. A postal match also is not a map location for the property; use a geocoder or a property data source when the exact location matters.
Two Texas addresses, checked live
We sent two Texas addresses to the sthan.io verification API on October 16, 2026, one in each kind of TWIA area. The county came back in both responses, although neither applicant typed it.
| Typed | Standardized | County | Other fields | What the county tells the quote |
|---|---|---|---|---|
| 823 Rosenberg Ave, Galveston, TX 77550 | 823 Rosenberg St, Galveston, TX 77550-2103 | Galveston | DPV Y, record type S, matchTier Near, footnote "street-type-corrected: AVE→ST" | Galveston is one of the 14 first-tier coastal counties TWIA lists by name, so the county answers the geographic part of the TWIA question. It does not settle eligibility, inspection requirements or underwriting |
| 604 W Fairmont Pkwy, La Porte, TX 77571 | 604 W Fairmont Pkwy, La Porte, TX 77571-6215 | Harris | DPV Y, record type S, matchTier Exact | Harris County is only partly covered, so the county is not enough. Check the property's actual location against State Highway 146 and La Porte's city limits; the postal match does not give that location |
Note the first row. The applicant typed "Ave", and the response corrected it to "St" and said so in a footnote. A quote saved with the typed version and a policy saved with the corrected one would not match each other. Store the standardized address from the start.
Autocomplete plus verification in one quote form
- While the applicant types, call address autocomplete after a short pause. Typing "604 W Fairmont Pkwy La" returned one suggestion in our test on October 16, 2026: "604 W Fairmont Pkwy, La Porte, TX 77571-6215". Picking it fills the street, city, state and ZIP+4 in one step (see address autocomplete for forms).
- On submit, verify the final address from your server, including any unit typed after the suggestion was picked.
- Act on the result with the table below.
- Save the standardized address, county, ZIP+4, record type and status with the quote, and the applicant's typed address next to it.
| Result | Quote form action |
|---|---|
| DPV Y | Continue with the standardized address and county. Y confirms a known postal delivery point, so keep your own checks for property location, eligibility and underwriting |
| DPV Y, a field corrected | Show "We updated your address to match postal records" with both versions; continue with the one chosen |
| DPV D (unit missing) or S (unit not confirmed) | Ask for the apartment or unit number, or ask the applicant to check it |
| DPV N or not found | Ask the applicant to check the street number and ZIP; let an agent take over if it still fails |
| Record type P or private mailbox Y | Keep it as the mailing address and ask for the property or garaging address |
Where sthan.io fits. sthan.io covers both steps of a quote form. Address autocomplete has 100,000 free requests a month, then $7 a month for 100,000. Address verification has 3,000 free requests a month (up to 100 a day, 10 a minute), then $12 a month for 10,000, and returns the standardized address, county, ZIP+4, unit, record type, private mailbox flag and deliverability status. No credit card for either free tier. sthan.io is not CASS-certified.
Frequently Asked Questions
Sources
All read October 16, 2026:
- NAIC, Regulatory Resources for Consumers on Personal Lines Pricing and Underwriting (2022), auto and homeowners sections.
- Maryland Insurance Administration and Maryland Auto, Report on Rate Assignment by ZIP Code (October 31, 2025).
- Texas Department of Insurance, Texas Windstorm Insurance Association Overview (October 1, 2026, for the quarter ending June 30, 2026), section "Coverage area".
- sthan.io API docs (record type and deliverability status values), What an Address Verification API Returns (DPV codes, private mailbox flag, fields not returned), the Address Verification and Address Autocomplete product pages (free tiers and prices).
- Two calls to the sthan.io US Address Verification API and one call to US Address Autocomplete, October 16, 2026.
This page describes address data only and is not insurance or legal advice.
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