You can submit an Employer Payment Summary (EPS) to HMRC to notify them about your reclaim small business rebate for NI contributions. I can walk you through on how to do that.
Please follow these steps below if you've subscribed to PaySuite:
Ensure you have run all weekly and monthly payrolls for the month.
Tick on Employees on the left pane and click Approved and Advance option.
Click on Make a different RTI Submission.
The second line on the form shows the Employer Payment Summary (EPS). Select on Submit to the right of the table.
Complete the form as necessary and click Submit EPS. You may not have anything to enter into the provided fields, however still click Submit EPS.
To give you more details about claiming the employment allowance in QBO, you may refer to this link: Employment Allowance.
However, if you're using Advanced or Standard payroll, you may follow the instructions found in these articles on how to send the EPS: