Quote from: squatter on January 05, 2018, 11:05:47 PM

If you deposited and withdrew BTC from Mintpal, those transactions are permanently recorded on the blockchain. It doesn't matter what transactions took place on Mintpal's internal database.

You sent BTC from Address A (which you can prove control of). You received a higher amount of BTC at Address B (which you can prove control of). The difference is your BTC profit, but what matters for taxes is the USD profit. Each trade on Mintpal is taxable, and the net of those gains determines your taxes due.

The fact that Mintpal no longer exists just makes it harder to disprove the records you provide for your Mintpal trades. That's why any good faith effort to pay taxes on the gains made between Address A and Address B is probably good enough. You made 4 BTC profit, which had a USD equivalent when you bought back BTC. That's your taxable gains.

When you cash out an amount of any relevancy, you must prove the origin. There is no real way to prove that the addresses where you deposited and withdrew from, are from Mintpal or from a drug dealer or anything else, because Mintpal doesn't exist, so there's no way to link them properly into the exchange, unless you can prove me otherwise, because all we got is some addresses on the blockchain now, without the context of the website. I don't know about the US, but in other countries you MUST prove the origin is not ilicit, and if they don't like the evidence, you risk losing your money because they would confiscate it or tax it to ridiculous levels.

So again, you send 1 BTC to Mintpal.

You make 4 BTC from trading it against some altcoin.

You send back your BTC to your wallet.

You end up with 5 BTC.

Now prove these addresses belong to Mintpal. And no, you can't prove ownership of the deposit address, because you don't control the private keys of a deposit address of an exchange, so you can't sign them.

Quote from: squatter on January 05, 2018, 11:05:47 PM

How can they definitively link addresses together? Personally, I am extremely careful about linking wallet addresses together, even if it means paying higher fees to consolidate outputs.

Well, if you are going to sell years worth of signature campaign earnings, they will ask where it came from and they will see the address is linked to your account where you posted at with a simple google search, then they could browse your posting history and track all of your receiving addresses for the signature campaigns.

Quote from: veleten on January 06, 2018, 02:32:11 PM

Quote from: gentlemand on January 01, 2018, 01:02:10 PM

Quote from: pereira4 on December 31, 2017, 08:13:31 PM

In this case, you are going to need to explain the origin of your coins, and im not sure how I would explain I made some BTC posting in some internet forum, this may not be convincing to them even if it's the truth.

-snip-
People deposit millions in banks from selling art made out of their own sperm and turds.

yeah some posts on this forum are no different in terms of quality or value Grin

I have never heard about banks asking about the origin of your coins
unless you go over a certain threshold or they come from tainted or flagged sources
if you are totally afraid to use banks,sell for WU,Paypal or any other electronic currency
sell here or at localbitcoins
get yourself a bitcoin debit card and fund it with bitcoins and cash out at any ATM
your options are limitless

They are not limitless, they are very limited, if the goal is to buy some real state. You basically have to be 100% transparent, pay all taxes, and be able to proof 100% that the gains are licit.