If you buy a cryptocurrency with the intention to hold it for the long-term, it will still have a real-time "paper profit/loss" based on the current market rate. However, in most jurisdictions a paper profit/loss would not be taxable.
Generally, cryptocurrency holdings are only taxable if/when you:
- sell or exchange them for another cryptocurrency or cash
- use them to purchase goods or services
- use them for margin trading
- gift them to someone else
- donate them to charity
(This list is not exhaustive and may vary based on your jurisdiction.)
IMPORTANT: Countries differ on how cryptocurrency transactions, trades and holdings are taxed (if at all) and how they view cryptocurrencies in general (e.g. as money, as property, as a commodity, etc). Please consult a local accountant, tax lawyer and/or government official for advice.