I'm not an accountant, but...

For a US citizen you should report any signature campaign taxes at the moment you sell your bitcoin. If you were paid in bitcoin for the signature campaign, the bitcoin you earned would change your cost basis. Now you earned an amazing 0.01 bitcoin for a signature campaign. Your cost basis for this 0.01 bitcoin is 0, since you didn't pay anything for it. To keep things simple, I would recommend keeping your bitcoin separate or keeping all the documentation you need to separate your dates on your tax forms. But lets imagine you didn't keep any documentation or the IRS thought your proof was insufficient. You will likely have to pay taxes on the full 0.01 bitcoins. If you sold the 0.01 bitcoins for say, $120 you would pay the capital gains tax of 15% on the full $120.