Depending on what software you're using (I'm using Sage Payroll), there may be an option to tick to say that the company is eligible for Employer's Allowance, which will result in an e-submission to HMRC to inform them that they are eligible. You may need to do that for future submissions as well as contacting HMRC to claim back past payments.
As an addendum to this thread, from April 2016 companies where the director is the only employee will be excluded from the allowance.
__________________
Shaun
Responses are not meant as a substitute for professional advice. Answers are intended as outline only the advice of a qualified professional with access to all relevant information should be sought before acting on any response given.