Types of Employment

Part-time support:
If your PA works for you on a part-time basis and you pay them less than £100 per week, but they have another job that brings their total earnings above the weekly threshold, you will still have to register as an employer as you may have to pay tax and NIC on their behalf.

Bear in mind that if you fail to comply with your responsibilities as an employer it is you HMRC will penalise, not your PA. Always find out if your PA has another job and ask them to put this in writing.