I left Thailand to visit my mother in the states for a few months. Whilst there I bought myself and girlfriend new MacBooks. 
 

Returning to Thailand and I’ll be bringing both along with my old one. 
 

The items are quite high value and should  I expect to be hit with import duty or do they only really do random spot checks? 
 

Flying into Swampy, fwiw. 
 

 

Just don't get stopped. 

I suggest you do not bring them in their original boxes and make sure you have used and personalised them so you can claim they are private.

The fact that you bring back 3 could be a problem. You might or might not be checked your risk.  I think nobody can give you any guarantees. Luck of the draw id say. 

Not visa or extensions related. Moved to the travel forum.

Three is dicey.

 

I've done two (Thinkpads), same-same, took current one, bought new one there, returned with two.

 

The duty-free exclusion remains 20,000 baht AFAIK, so you'd potentially be in excess of that. Are you traveling alone? (This exclusion is 40,000 for a family.)

 

I used to bring a lot of PC kit back - enough to build one or two desktops - and did not encounter any issues at the Customs (Green channel) exit, even though bags were x-rayed.

 

The dilemma is running the Green channel risk, or going through the Red channel and declaring the items, and at worst, paying 7% VAT.