HMRC have provided a tax free incentive for filing the P35 Employer Annual Return online for a number of years now.
The exercise must have been successful because the incentive has been reduced and is about to be phased out.
If you have fewer than 50 employers, you don’t have to file online until at least 2010 but you can get a tax-free payment of £75 for doing so before then.
Check out the HMRC website for more information.