The first transaction in every Bitcoin block, created by the miner, which generates new Bitcoin as the block reward plus collects all transaction fees from the block. This is the only way new Bitcoin enters circulation.
The first transaction in every Bitcoin block, created by the miner, which generates new Bitcoin as the block reward plus collects all transaction fees from the block. This is the only way new Bitcoin enters circulation.
Every Bitcoin block begins with a special transaction called the coinbase transaction (not to be confused with the exchange of the same name). Unlike regular transactions that spend existing UTXOs, the coinbase transaction has no input — it creates new Bitcoin out of thin air according to the protocol's issuance schedule. The miner who finds a valid block gets to construct this transaction, directing the block reward plus all included transaction fees to their own address.
The coinbase transaction is Bitcoin's monetary policy in action. The block reward started at 50 BTC in 2009 and halves every 210,000 blocks (approximately every four years). After the 2024 halving, the reward is 3.125 BTC per block. This declining issuance schedule is hardcoded into the protocol and will continue until approximately 2140, when the last fraction of a Bitcoin is mined. After that, coinbase transactions will contain only transaction fees.
Miners can include up to 100 bytes of arbitrary data in the coinbase transaction's input field. Satoshi famously embedded the headline "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks" in Bitcoin's genesis block coinbase. This tradition continues — miners regularly embed messages, pool identifiers, and signaling data in their coinbase transactions, creating an indelible record within the blockchain itself.
No. The coinbase transaction is a Bitcoin protocol concept that predates the exchange by years. The exchange chose its name as a reference to this fundamental Bitcoin mechanism. In technical discussions, "coinbase transaction" always refers to the block reward transaction, not the company.
Only the miner who successfully mines a block can create its coinbase transaction. The protocol enforces strict rules: the reward amount must match the current subsidy plus fees, and the coinbase output cannot be spent until 100 blocks have passed (the coinbase maturity rule). Any violation makes the entire block invalid.
Coinbase transactions will still exist in every block, but the block subsidy portion will be zero. Miners will collect only transaction fees. This transition is gradual — the subsidy becomes negligible long before 2140. Bitcoin's fee market must generate sufficient revenue to incentivize mining and maintain network security.