A Home Office reference number is a unique identification number given by the UK Home Office to individuals who have submitted an application related to immigration, citizenship, asylum, or other related matters. It is also sometimes called a "unique application number" (UAN) . The reference number is critical for tracking applications and getting information about their status.

The Home Office reference number is usually provided when an individual first applies for a visa or other immigration-related matter. It can be found in various documents, such as visa approval letters, emails, or other correspondence from the Home Office. In some cases, the reference number may be a 16-digit number, separated by dashes, and starting with the numbers "1212".

It is important to provide the Home Office reference number when requested, as it helps to ensure that the correct application is being processed and can speed up the processing time. If an individual cannot find their reference number, they may be able to look it up via an online system or by contacting the Home Office directly.