However HMRC will consider reducing the penalties if the employer has a 'reasonable' excuse for being unable to make the payments by the appropriate due dates. So what constitutes a reasonable excuse?
Recent success has been achieved by proving to HMRC that cash flow issues beyond the control of the employer have prevented the payment from being paid on time. This can be in the form of proving a bad debt (money expected not received) or refinancing from the bank expected but delayed due to no fault of the employer.
Remember HMRC do make mistakes so it is important to check any Penalty is correct and to challenge where appropriate.