Coinbase transaction
A coinbase transaction is the first transaction in every Bitcoin block, which pays the miner the new coins and the fees (not the Coinbase exchange).
The first transaction in every block, which pays the miner the new coins and the block's fees. It has no inputs, and miners write a short note in it, often their pool's name.
How is it different from other transactions?
It has no real inputs: it creates new bitcoin instead of spending old ones. Its outputs may pay out no more than the block reward plus the block's fees, and they can only be spent after 100 more blocks.
What do miners write in it?
The coinbase has room for up to 100 bytes of free text. Pools put their name there, and since block 227,931 it must start with the block's height. The genesis block's coinbase holds a newspaper headline from 3 January 2009.
Sources
Updated 10 Oct 2026
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