Does it matter if SMP is done before or after a HT surgery?

The planning of SMP and hair transplant should be discussed between you and your doctor.  There is no right or wrong order in which you have the procedures.  It has more to do with the individual and the planning.

porterj89,Thank you for your question about scalp micropigmentation. You definitely want to wait until the scalp is healed after a hair transplant before you do any additional work. Because SMP is fairly superficial and tends to be .5 to .7 mm deep, it shouldn't disturb the transplant, but I prefer to wait until I see the growth from the transplant. 
If you perform an SMP procedure prior to a transplant, it's a bit harder to work in the area - it can still be done - it's just a little more difficult. This way the transplant will grow in gradually without detection and increase the density look to your hair outcome.
Thank you, 

Dr. Arocha

SMP would not be a problem in regards to a surgery being done on someone who has had SMP.  However if you are planning a surgery, it may be best to wait until after you have had results of regrowth and scars from the surgery have fully healed, in order to have a more effective placement of the SMP that will also help cover the scars.  Good luck!!