exemption from class 2 ni

Please could someone help with my question:

If Mr A earned £20,000.00 in his employed employment, obviously over the threshold and he will have to tax and ni, I understand that part.

Then if Mr A (the same person) was to start working as self emplyed as extra income but it was below the threshold to pay class 2 ni (£5075) am I correct in saying that Mr A would be able to claim an exemption from class 2 ni because it is below the threshold even though he has employed employment also???????????