The Postcode Address File (PAF) is Royal Mail’s database of every address in the UK that it delivers post to, each matched to its correct postcode and set out in Royal Mail’s standard format. Most address lookup boxes on UK websites, where you type a postcode and pick your house from a list, draw on it.
How the Postcode Address File works
Royal Mail maintains PAF and updates it continually as homes are built, buildings are split into flats, businesses move and streets are renamed. Each record breaks an address into set parts: an organisation name where there is one, the sub-building and building name or number, the street, a locality where one is needed, the post town and the postcode. Postal counties are not part of the record, because Royal Mail stopped needing them long ago, which is why a PAF address often reads differently from the version people write by hand.
Businesses rarely buy PAF directly. Instead they use a licensed address lookup provider, which loads the file into a service that a website form, checkout or CRM can call. The customer enters a postcode, the service returns the matching addresses, and the one they pick is saved in a clean, consistent format. To see how Royal Mail formats a single address, you can use its free online postcode finder, which limits how many searches you can make each day.
Why it matters
For local search, PAF gives you a reference version of your own address. Google, directories and data aggregators all try to match the address on your Google Business Profile with the one on your website and on every local citation. If one listing says “Unit 4, 12 Mill Lane, Leeds” and another says “12 Mill Ln, Unit 4, Holbeck, West Yorkshire”, a person sees the same place but a matching system may not. Choosing the PAF version and using it everywhere is the simplest route to NAP consistency.
On forms and checkouts, PAF-based lookup saves typing on a phone, reduces failed deliveries and gives you cleaner data for posting mail and for seeing which areas your customers come from. Fewer fields to fill in also gives people fewer reasons to give up halfway.
Common mistakes
- Typing the address slightly differently on every directory, adding or dropping the county, the locality or the unit number.
- Using the PAF address on citations but a shortened or tidier version in the website footer and on the Google profile.
- Assuming a brand-new building appears in PAF straight away. New addresses can take a while to be added, so always keep a manual entry option on forms.
- Forcing lookup with no fallback, which locks out anyone whose address is missing or unusual.
- Using addresses captured at checkout for marketing post without saying so in your privacy notice. An address is personal data under UK GDPR however it was collected.
How to act on it
Look up your business address in Royal Mail’s postcode finder and copy the result exactly, line by line. Make that the master version and keep it in the document where you record your business details. Then update your website footer and contact page, your Google Business Profile, and your listings on directories such as Yell and the trade sites in your sector so they all match it.
If your website takes addresses, test the form on a phone. Check there is a postcode lookup, that it handles flats and business names properly, and that someone whose address is not found can type it by hand. Checking every citation against a single master address is part of the local SEO work I do for UK businesses.