As an employer you may be eligible to claim back up to £3000 from HMRC for Employer (not Employee) NI Contributions. Please click on this link to Gov.uk website and read their guidelines to ascertain your eligibility.
If you are eligible then you need to amend a field in your Employer Details Screen in your Enrolpay Portal.
The path is as follows:
Employer/Details/Claim Employment Allowance - change indicator to YES/SAVE
You will then need to submit an EPS once only in the relevant tax year to trigger the claimback. The EPS field is found in the Real Time Information Screen within Submissions.