I'm picking a mate up from the airport soon. He works in the UK for the British subsidiary of a German manufacturer. His visit is for his employer to instruct a new Thai stockist on how to fit/operate their products. When he told me he was coming over for work I asked him if he'd obtained a visa/work permit, he said he thought the company had arranged everything. I asked him if they had asked for his passport - no. So I told him I doubt he had any sort of visa or work permit as the company would have needed his passport to obtain a visa.  The work he'll be doing will be inside a factory behind closed doors and he'll be here for just 5 days so I doubt there's much chance he'll be seen but I've told him that as far as I know, he should have a work permit/visa. I told him that if he intends to continue with the trip he should not mention what he'll actually be doing when he gets to immigration - better to say tourism/visiting me.  I think his company have been very slack on this - this is not the first time they've sent someone abroad to instruct stockists, they should know that visas and work permits are required for a lot of countries.  What should he actually have for this trip? - he will be instructing but I'm pretty sure he'll have to carry out some welding etc. in order to carry this out.

He should probably have a non-immigrant B visa and a temporary work permit: http://www.thailawonline.com/en/business/work-permits/temporary-work-permit.html

Seems they changed the name from WP11 to WP10 https://www.doe.go.th/prd/assets/upload/files/alien_en/3ce03a7d9178d0ca0ff302a45e8b11e7.pdf

My thoughts are, UBJ is needed, that less than 30 days to do what he going to do doesn't need a WP. 

Visa status may require a single entry B and that should not be too difficult in UK.

It sounds like work to me. In which case your friend should have a non ‘B’ and permission to work.

 

I doubt the authorities would be too bothered by what he’s doing, but your advice not to mention his work to immigration is correct; unless he states he’s only attending meetings, which is exempt from needing permission.

3 minutes ago, overherebc said:

My thoughts are, UBJ is needed, that less than 30 days to do what he going to do doesn't need a WP. 

Visa status may require a single entry B and that should not be too difficult in UK.

It doesn’t matter if it’s only 1 day. If you’re working you need permission unless the work is exempt. The employer should have applied for temporary (15 day) permission to work.

19 minutes ago, elviajero said:

It doesn’t matter if it’s only 1 day. If you’re working you need permission unless the work is exempt. The employer should have applied for temporary (15 day) permission to work.

Aren't people allowed to attend seminars company meetings sign company papers demonstrate new company equipment for a few days etc without a WP nowadays?

Thailand has just relaxed its rules on work permits. If these 5 days just involve him attending meetings at a business site then he probably wont need a work permit: 

 

15 minutes ago, overherebc said:

Aren't people allowed to attend seminars company meetings sign company papers demonstrate new company equipment for a few days etc without a WP nowadays?

Certain activities are exempt, but it sounds like the OP’s friend is training which I don’t think would be.

 

Very little has changed regarding who needs a work permit or exempt work.

As I said previously, I think he will have to carry out some welding etc. I used to work for the same company so I know what's involved - I don't see how he can instruct without actually doing some of the work - especially with the language barrier. I know what I'd do if I was him - I'd get here, call the company, tell them I need a work permit and let them sort it out - he might get 10 days instead of 5 that way. ?

23 minutes ago, KhaoYai said:

As I said previously, I think he will have to carry out some welding etc. I used to work for the same company so I know what's involved - I don't see how he can instruct without actually doing some of the work - especially with the language barrier. I know what I'd do if I was him - I'd get here, call the company, tell them I need a work permit and let them sort it out - he might get 10 days instead of 5 that way. ?

Assuming he's not entering with a non 'B' visa that would cause more problems as he would need a non 'B' visa before the company could apply for the work permit. I think getting formal permission before he is due to work is unlikely.