From 6th October 2014 HMRC will apply penalties for late submission of FPS or EPS. FPS is the submission which needs to be made to HMRC on or before your employees are paid. An EPS may also need to be submitted if you need to report recoverable amounts such as SMP or need to report that no employees have been paid.
The penalty payable will depend on the number of employees on your payroll. For 1 to 9 employees you will pay £100 for each late submission and for 10 to 49 employees you will pay £200. Penalty notices will be sent quarterly in July, October, January and April. As the penalty amounts are monthly you could already have incurred 3 months worth before you are even aware your FPS or EPS has not been submitted.
HMRC will accept a reasonable excuse for non filing and set out some of these on their website. However pressure of work, or the fact that HMRC did not remind you will not be considered as a reasonable excuse.
For further information on late filing penalties visit http://www.hmrc.gov.uk/payerti/reporting/late-reporting.htm.