Self employed NIC

If both employed and self employed do you pay class 4 national insurance if profits from both incomes go over 12,570 or do you pay only if self employment income goes over 12,570? Considering national insurance on the employment income has already been paid from paye. What if profit is between £6,725 and 12,570 is there any NI to pay then?

Hi,
All information on paying class 4 can be found here Self-employed National Insurance rates - GOV.UK
When completing your SA return if NICs are due you will be prompted to pay the NI accordingly.
Thank you.