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What is a coinbase transaction?
A coinbase transaction is the first transaction in every Bitcoin block, written by the miner who built it. It creates the block's new bitcoin and collects the block's transaction fees, paying them to addresses the miner chooses. The name is a technical term and has nothing to do with any company.
What it means for you
Bitcoin paid out by a coinbase transaction, such as a solo miner's reward, cannot be spent until 100 more blocks are mined, about 16 to 17 hours at ten-minute blocks. It is the only way new bitcoin enters circulation, so it has no sender: the coins did not come from anyone's earlier transaction.
How it works
Every block's transaction list must begin with one coinbase transaction, also called a generation transaction. Rather than spending earlier coins, it claims the block reward: the block subsidy plus the fees left by every other transaction in the block (inputs minus outputs). The whitepaper describes it as the way coins are first put into circulation, since no central authority issues them. In pooled mining, the block template includes a coinbase transaction paying the pool. Its outputs carry a special rule: they cannot be spent for at least 100 blocks.
Sources: Bitcoin Developer Guide: Block Chain, Bitcoin: A Peer-to-Peer Electronic Cash System (whitepaper), Bitcoin Developer Guide: Mining · checked 4 October 2026
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