From 6 April 2013 all employers will have to start reporting PAYE information to HMRC in real time.
They will be required to send detailed information to HMRC online every time they pay an employee, at the time they pay them. The way new employees and leavers are reported to HMRC is also changing.
Find out more about how I can help you prepare for this change on my dedicated RTI page
Detailed information can be found on the HMRC website http://www.hmrc.gov.uk/payerti/getting-started/index.htm