Employers should file their PAYE end-of-year returns by 19 May, or they could face a penalty. Those with 50 or more employees must file online this year.
Employers with fewer than 50 members of staff file either on paper or online, though they will receive £100 tax-free if they file their returns electronically.
Businesses that want to start filing online must first register with HMRC's online PAYE service. It may take up to a week to receive an activation PIN after registering, so it is important to register as soon as possible.
Help and advice can be found on the HMRC website, via the employer helpline on 08457 143 143, and on a recent HMRC video podcast covering employer filing online.