Short answer
Keep the date, token, amount, value at the time, fees paid and transaction ID for every trade and transfer. On-chain history helps, but your own export is easier to work with.
Most tax calculations need to know what you paid for each token, what you received when you disposed of it, and any fees. Transfers between your own wallets matter too, so they aren't mistaken for sales.
Every DYOR trade links to its Solana transaction, which is a permanent public record. Exporting your history regularly, and noting which wallets are yours, will save hours later.
Rules about what counts and how to calculate it vary by country. Use this as a checklist to discuss with a tax professional, not as advice.
General information, not tax advice. Rules vary by country and change over time.
See the checks for yourself
18+ only. Self-custodial: you keep your keys. 0.5% per trade, no minimum. Memecoins can go to zero.