The seller’s realtor was skeptical that it was legitimate money because my proof of origin of funds was from a crypto exchange Edit: Sorry I disappeared, I was buying a house! it is an investment property less than 50 miles away (and I’m not selling my home), and I’m retired so I couldn’t get a mortgage (you qualify by debt to income ratio only, assets don’t count for investment property apparently). I found out the day before closing. So I had to sell some precious bitcoin to pay cash. So yes, now I will have to pay taxes on my BTC gains, in addition to all the other taxes. Theoretically however, even if I straight up purchased with BTC, I would still have an obligation to pay taxes on the gains.