In the US
Buying digital assets with US dollars, and holding them, are not reportable transactions on their own. Moving them between wallets or accounts you own is not either, unless you paid a transaction fee with digital assets, because paying a fee in crypto is a disposal of that crypto.
So if all you did in the year was buy and hold, you can generally answer "No" to the digital asset question on Form 1040 and have nothing to put on Form 8949.
In the UK
Buying cryptoassets is not a disposal, and moving tokens between public addresses you control is not one either, because you keep beneficial ownership. Capital Gains Tax only comes into play when you sell, swap, spend or give tokens away.
Records to keep from day one
- The date and time of each purchase, the amount bought, and what you paid, including fees.
- Which exchange account or wallet the coins went to, and every transfer between your own wallets after that.
- In the UK, values in pounds sterling and your running pool cost for each token type.
- Exchange statements and bank statements showing the payments. Exchanges can close or lose history, so download them now.
When it becomes taxable
In the US, selling, swapping for another coin, or paying for something with your Bitcoin creates a gain or loss. Holding for more than a year before you sell gets the lower long-term rates. In the UK, the same events are disposals, and gains above the £3,000 allowance are taxed at 18% or 24%. The country guides explain each step.