I know for watches (e.g. you buy one + put it on), customs can ask to supply them with the original purchase invoice or some sort of transaction statement. It's

I know for watches (e.g. you buy one + put it on), customs can ask to supply them with the original purchase invoice or some sort of transaction statement. It's probably easier with a laptop because you can put it in a bag, but nevertheless, it's not completely safe to do.