Your matching strategy should define your rules for matching and what should happen when:
- a matching record is found
- multiple records are found that could be a match
- no match is found
It’s up to each service to decide their own matching strategy, but this guidance provides an overview of things to consider.
Contact the GOV.UK Verify team for help deciding and implementing your matching strategy.
Common matching difficulties
You need a matching strategy because matching an identity to a record is often affected by problems such as:
- spelling mistakes
- transcription errors
- twins with very similar information
- incorrect or outdated information in your service’s data sources, for example, if someone has moved house or changed their last name
- inconsistent use of upper and lower case letters in names, for example McDonald, MacDonald, and Macdonald
- variations with special characters, for example the difference between an apostrophe and single quotation mark in O’Reilly
- the use of shortened names or nicknames for the same person, for example, William Smith, Bill Smith and David William Smith
- date transposition for birth date, for example 02/07/1962 and 07/02/1962 or typos such as 1989 and 1998
- phonetic spellings, for example if the data was collected in phone calls
- an individual removing diacritical marks from their data, for example inputting Günther as Gunther
Matching can also be affected by changes to the data since it was collected. For example, if the schema for the datasource changes.
Different identity providers will use different data sources to check an individual’s identity. Because of this, the data you receive from one identity provider through the GOV.UK Verify Hub may look different to data from another identity provider. For example, if an individual does not have a middle name, one identity provider might list it as ‘null’ when another identity provider might leave the attribute blank.