In order to buy a house you will need to exchange your bitcoins for Fiat. You can always pay taxes with this amount and I think that tax authorities will not claim you. How can they trace the path of your coins? You can buy bitcoins in 2010. If you have concerns you can always arrange a mortgage and repay the debt installments.
Yes, I would like to add that you can't buy a house directly with bitcoins for now and you will have to cash out your coins to buy it. When the bank/government/tax service will see a big sum of money on your account they may ask you to explain where this money come from and if they count it as profit you will need to pay personal tax as well.
Guys try reading my thread before replying. I know that I can't buy a house with bitcoins and I would need to cash out. Im talking about the problem of how if you mixed that BTC, you will not be able to prove the origin of that BTC.
If you buy 1 BTC, and 2 years from now it's $100,000, you will have the receipt of the exchange to prove that you bought it, so you just have to pay capital gains tax on that.
If you mined 1 BTC, you can prove that it was mined by you for example signing the public key where it is proven that you had that private key that was freshly minted by you. Im not sure hot taxes go with mining but the point is you could prove it was legally acquired.
If you make here in the forums 1 BTC across years of posting in sig campaigns, or early on when you could make 0.5 BTC per month easily, you could prove that you made them posting here by for example, signing the public key that you posted here to get paid in the campaigns. (again not sure how taxes would work in this case, but you could prove you got this BTC legally)
The problem is, if you mix that 1 BTC in a mixer, you can no longer prove the origin because the mixer makes it a mess to prove in the blockchain, and I would be scared to sell that mixed 1 BTC... you know what I mean now?