Policy & Research
Background briefings
Understanding your postal address
When sending mail to UK addresses you need to provide a full and accurate address complete with postcode. The diagram below shows the correct information and how to present it.
Make sure you include the postcode as this will allow your item to be processed quickly and accurately. If you do not know the postcode you can use Royal Mail’s postcode finder service (details on Royal Mail’s website). You do not need to include a County name provided you use the post town and postcode. Avoid using commas or full stops and do not centre or stagger your lines.
If you write a return address on the back of the item it can be returned to you in the case of delivery failure.
Why do I need to use a postcode?
The importance of using postcodes becomes clear when you understand how they work. Each part of the postcode provides step-by-step information about where the item of mail is heading. From left to right the postcode narrows down its destination. Take Consumer Focus’s own postcode – SW1P 1RT:
| SW | 1P | 1 | RT |
|---|---|---|---|
| The first 1 or 2 letters represent the postcode area, identifying the main sorting office that will process the mail. | The second part is usually just 1 or 2 numbers but, for some parts of London, can be a number and a letter. It denotes the postcode district, telling the sorting office which delivery office the mail should go to. | The third element is usually just 1 number. This tells the delivery office which local area or neighbourhood the mail should go to. | The final part of the postcode is always 2 letters, identifying the unit. There are, on average, 15 addresses per unit, telling the delivery office which postal route will deliver the mail. |
Using the postcode means that items can go through Royal Mail’s automated sorting machines. If mail does not have a postcode, it will have to be sorted manually which takes longer.
Can my postal address be changed?
Changes to postal addresses can be made for one of two reasons:
- To maintain or improve Royal Mail’s service. Royal Mail tries not to change addresses whenever possible. However, occasionally it needs to change the way it routes mail to provide a better service, eg if a new delivery office is built, or it runs out of postcodes to allocate to new homes and businesses.
- To reflect customer demand. Royal Mail’s first priority must be to ensure that it can deliver mail efficiently to its customers. Royal Mail may amend particular elements of the address in response to customer demand. In each case, specific criteria need to be met before a change can be made.
The postcode address file (PAF)
The postcode address file (PAF) is the central database, owned and managed by Royal Mail, that holds all the postcodes and postal addresses – approximately 27.5 million of them – in the UK. It is a cornerstone of Royal Mail’s postal business.
Royal Mail’s postal competitors also rely on the PAF for sorting, transport and delivery of mail throughout the UK. In addition it is widely used by UK industry to help identify correct postal addresses and to cross reference postcode and address data against other databases, for example:
- marketing companies use it to generate addresses for their customers
- insurance companies often use it as one of the tools to group and profile customers to assess premiums
- it helps local government manage the electoral role
- the NHS uses it to link patients with NHS codes
