when he signed the employment contract it was clearly stated the minimum required sales from him...and if he fails to meet this amount for 3 months in a row, we have the right to terminate his contract.

he has been working for 5 months, out of which 4 months were probation months. must we pay him 1 month severence pay?

I was of the understanding any time employed during a probational period was not calculated into any potential severance payout.

Why didn't you terminate him at the end of his probation?

Would seem to have been the obvious opportunity.

i thought severence pay includes the number of months that he's on probation....?

he has put in effort but somehow no good results....for the last 2 months he didnt meet the minimum required sales target. if for 3 months in a row he doesn't meet the target, the contract says we can terminate him. but do we have to pay severence?

You do need to pay 1 months severance pay to him. even at the end of probation you still need to pay 1 month to terminate him.Thai Law. I have a copy in English and just checked it out for you.

so in this case, it is 1 months pay on top of what you owe him for his working hours.