Coinbase customers For all transactions, you need the cost basis of each transaction — the amount in dollars that you spent originally to buy it — and the amount in dollars it was worth when you sold it. This will be used to calculate your gains and losses.
How does Coinbase calculate gains?
For each transaction for which we have a record, Coinbase calculates your gain or loss by taking the proceeds you received, and subtracting the cost basis (i.e., the price at which you originally bought or received your crypto).
How does Coinbase pay interest?
Coinbase has announced that it'll let users earn interest on their cryptocurrency by lending it to a decentralized finance app called Compound (via Bloomberg).9 Dec 2021