A "billing address" is the address your card issuer holds for the account — not where a parcel goes. On UK cards, automated verification (AVS, the Address Verification System) compares exactly two things against that record: the house number and the postcode. Not the street, not the town, not the county. That single fact explains most of what happens on UK checkout forms — what passes, what fails, and which fields are decoration.
A UK address runs from the specific to the general, and the postcode always comes last:
Flat 2, 12 Wellington Road. The number attaches to the street with no comma; the flat always goes in front.Marylebone. Leave it empty if the form allows; never put the town here.London or Leeds, on its own line.NW1 6XE.There is no state or province in a UK address. On American-style forms that force a State box, the accepted practice is the county or "N/A" where the form permits it.
Most international checkouts are built US-first. When you select "United Kingdom", the fields reshape — here is what maps where:
| US-style field | UK reality | What to enter |
|---|---|---|
| Address line 1 | Same slot, different convention | Number first, then street (US forms accept this fine) |
| Address line 2 | Optional locality | District, or empty — not the city |
| City | Town / City | The postal town that matches the postcode |
| State | Does not exist | County or "N/A"; "England" is not a city |
| ZIP (5 digits) | Postcode (alphanumeric) | Full postcode with the space — never digits only |
NW16XE is the same postcode as NW1 6XE, but strict validators reject it. Normalise: one space before the final three characters.CR0, where district zero is real.Form asks for Name / Address / City / State / ZIP, country selector set to United Kingdom:
| Field | Entry |
|---|---|
| Address line 1 | 27 Brompton Road |
| Address line 2 | Knightsbridge (optional) |
| City | London |
| State | Greater London or N/A |
| ZIP / Postcode | SW1X 7XL — letters, digits, and the space |
What the processor does with it: extracts 27 and SW1X 7XL, compares against the card record, and ignores the rest for verification purposes (the full address still travels for fraud-scoring and delivery). This is why the two fields worth triple-checking are the house number and the postcode.
If you are building or testing a checkout rather than filling one, a UK test address needs three properties at once:
The UK address generator on this site produces exactly that: real town, real outward code, synthetic house number and inward code — a format fixture whose complete postcode or address is not verified and may coincide with a real household. For UK tax questions ("is a UK address tax-free?"), the short answer is in the tax-free explainer; for real payments, use your real billing address — test data is for testing forms, not for paying with.
House or flat number + street on the first line, an optional second line for locality, the town or city on its own line, county optional, and the postcode last — e.g. "Flat 2, 12 Wellington Road / Marylebone / London / NW1 6XE". There is no state field in a UK address.
The UK equivalent is the postcode — alphanumeric, 5–7 characters, always ending in one digit then two letters (NW1 6XE). It is not a 5-digit number: a form that only accepts digits is built for US ZIPs and will reject every UK postcode.
Only two things: the numeric part of the address (the house number) and the postcode, compared against what the card issuer has on file. The street name is not checked — which is also why a perfectly typed street with a wrong postcode still fails.
No — Royal Mail sorting relies on the postcode, and county has been optional in formal addressing for decades. Include it when the form has a dedicated field; never sacrifice the postcode for it.