Change of sponsor

Hello, Not sure if you are still looking for an answer on this. Anyway, my 0.02

It depends on the type of contract with his off-site employer and his employer itself (some companies get their employees to sign a bond when they go to over seas onsite assignments). If there is nothing of such sort with your candidate, there will surely be a notice period (between 1 - 3 months for which the employer can hold him). While some companies are lenient on this, some turn really ugly if an on-site employee resigns (demands the employee to de-register and go back yo India to complete the resignation formalities, threaten legal action, etc).. Again, it all depends on the employer, their HR and the type of contract.