From 1 December 2012, the requirement to provide the UK Border Agency with biometric information is changing with the introduction of biometric residence cards.
If you are from outside the European Economic Area or Switzerland and you are granted permission to stay in the UK for more than 6 months on or after 1 December 2012, you must apply for a biometric residence card (if you have not already done so). If you are affected by the change the UKBA Home Office will write to you about how to apply for your biometric residence permit.
This is to ensure that from 1 December the UKBA Home Office only issue this new format of immigration status document. This is to meet their obligations under European legislation.
Biometric residence permits are replacing older forms of documentation and the new format is helping employers and other bodies to check the immigration status and entitlements of foreign nationals. They are both simpler to understand and are more convenient for foreign nationals living in the UK to use. The application process also enables the agency to check a person against both their records and police fingerprint records.
The UKBA Home Office have been rolling out biometric residence cards to different visa categories over the last 4 years. This means that applicants have been enrolling their biometric information (fingerprints and facial images) to apply for a biometric residence permit at the same time as making their application to stay in the UK. Some people will have applied to stay in the UK before there was a requirement to provide biometric information in their category, and will not have provided their biometric information. If these people are granted permission to stay on or after 1 December 2012, either at first consideration or after a successful appeal, they will need to apply for a biometric residence permit.
(via UKBA)