Question: i want to electronically send money to my wifes father to build a house. The money is derived from both of use working in Australia (my wife is a permanent resident in Australia and has a full time job).

What is the best reason to put for bringing the money in, someone told me to put 'personal expenses'as money for a house abroad can get abit messy as you then have to prove how the money was earnt ( especially for the thais) as apparently you are not allowed to send money to Thai people for this purpose (i could be wrong ??)

I have never heard about being asked where the money came from when bringing money into Thailand, only when sending it out. I have never been asked over the past ten years. Even when I last sent 12,000USD to the U.S. I only had to say it was for my father and it went through, no problem.

are you asking for the Australian side or the Thai side?

And how much money are you wanting to transfer?

Restrictions For Incoming Money, Are there any restrictions for transferring money into Thailand

On many, many electronic transfers I have never been asked where the money came from, I was was asked on one occasion, and one occasion only, (via phone) what I intent to do with it, I gave my reply, and the matter was completed within 30 seconds.

My Thai bank held up money that I was transferring in with the declaration of "buying a condo" until I showed them the purchase contract as proof.

The question is more about if you want to ever take the money out. If not, then personal expenses is probably fine.