How Does a Bitcoin Coinbase Transaction Create Miner Rewards?

Crypto Basics

25 October 2026

Bitcoin miner rewards are not created by taking a "cut" from transfers between users. Instead, they are "issued" out of thin air by the first special transaction in every block: the coinbase transaction. This transaction has no real sender. It pays the newly issued bitcoin (the block subsidy) plus all transaction fees in that block directly to the miner or mining pool.

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Coinbase Transaction: The "First Entry" in a Block

Every Bitcoin block contains exactly one coinbase transaction, and it is always placed first in the block. Normal transactions need to reference the output of a previous transaction as an input to prove "this money is mine to spend." A coinbase transaction has no such input. It is the only mechanism in the Bitcoin system that can create new coins from nothing.

How much this transaction can "issue" has a strict upper limit. The protocol states that the total value of a coinbase output cannot exceed: the current block subsidy plus the sum of all transaction fees in that block. If a miner tries to write even one satoshi more, the entire block will be rejected as invalid by full nodes.

Block Subsidy: The Only Source of New Coins

The block subsidy is the truly "newly issued" bitcoin. At the genesis in 2009, it was 50 BTC per block. After that, it is cut in half every 210,000 blocks (about four years). After the fourth halving in April 2024, the current subsidy is 3.125 BTC. Following this schedule, the subsidy will continue to decline until it approaches zero around the year 2140.

So if you ask "how do transactions create rewards," the accurate statement is: transactions themselves do not create new coins. New coins are issued by the coinbase transaction. Regular transactions contribute fees, while the subsidy is added separately by the protocol.

Transaction Fees: Riding Along with the Coinbase

When you transfer bitcoin on the network, the fee you pay is the difference between the total input and the total output. This leftover amount stays in the block. When a miner constructs the coinbase transaction, they can include these scattered fees in their own output amount.

This means the value of a coinbase transaction is not fixed for every block. The subsidy is 3.125 BTC, but after adding fees, what a miner actually receives may be slightly more. When the network is congested and fees are high, the total coinbase value increases accordingly. When the network is quiet, the difference is smaller.

Where Do Rewards Go Under the Mining Pool Model?

If you are solo mining and are lucky enough to find a block, the coinbase pays you directly. But today, the vast majority of hashrate is in mining pools. In this case, the coinbase payout address is that of the mining pool, not the individual miner who happened to submit the valid share.

After the pool receives the subsidy and fees from the coinbase transaction, it distributes the earnings to participants according to its own payout rules (such as PPS+, PPLNS, etc.). A common misunderstanding is "my miner found the block, so the reward is mine." Under a hosted pool model, finding a block simply gives the pool income to distribute. Your income still depends on the valid shares you contributed and the pool's settlement method.

An Easily Overlooked Time Gap: Maturity

Although the coinbase transaction is written into the block, its output cannot be spent immediately. The Bitcoin protocol requires that a coinbase output created in block N can only be spent in a transaction in block N+100 at the earliest. This rule prevents newly mined rewards from disappearing if the chain is reorganized.

However, a mining pool can "credit" your account earlier than this limit. When the pool records your earnings in its internal database, that is just a database operation. It does not mean the on-chain coinbase can actually be moved yet. If the pool wants to send you an on-chain payment before maturity, it must use its own other available funds.

So, Back to Your Question

"How does a Bitcoin coinbase transaction create miner rewards?" The answer chain is: a miner or pool constructs the coinbase transaction → fills it with 3.125 BTC subsidy + fees in the block according to the protocol limit → points the output to itself → after the block is accepted by the network, this coinbase becomes spendable bitcoin (after 100 blocks) → under the pool model, the pool then distributes earnings to miners based on shares.

Transactions themselves do not "generate" rewards. They contribute the fee portion. The action that truly creates new bitcoin only happens inside the coinbase transaction.

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