Bitcoin's issuance follows a fixed schedule: the block subsidy halves approximately every 210,000 blocks (roughly four years) starting from 50 bitcoin per block, and this geometric halving means the subsidy rounds down to zero around the year 2140, at which point the 21 million supply cap will have been effectively reached (with the last fractions distributed in tiny amounts over preceding decades).
From that point forward, the only reward for mining a block is the transaction fees included in it. Miners currently already earn a mix of subsidy and fees, and fees already dominate revenue during periods of high demand for block space, so the transition is gradual rather than an abrupt cliff, by the time the subsidy is negligible, the network will have had over a century to develop a functioning fee market.
The Bitcoin whitepaper explicitly anticipated this transition, describing the incentive shifting from new coins to transaction fees once the cap is reached. What is genuinely not settled is whether transaction fee revenue alone will consistently be high enough to secure the network at a similar level of hash rate as today, especially if most everyday payments move to layers like Lightning that batch many payments into few on-chain transactions.
Explain more simply
New bitcoin is created as a reward every time a miner finds a block, but that reward is cut in half roughly every four years and will eventually round down to zero.
After that point, around the year 2140, miners will only earn money from the fees people pay to get their transactions included, not from newly created coins.
Real-world analogy
It is like a construction subsidy that tapers off over a century while tenants gradually start paying enough in rent (fees) to cover maintenance on their own. Whether the rent will always be enough is the open question, not whether the subsidy ends.
Key facts
- The block subsidy halves roughly every four years and rounds down to zero around the year 2140.
- After that, miner revenue comes entirely from transaction fees.
- Whether fee revenue alone will sustain current security levels long-term is an open, debated question, not a settled fact.
Common misconception
“Once new bitcoin stops being issued, mining will stop being profitable and the network will fail.”
The transition to fee-only rewards is gradual and was anticipated from the start; fees already make up a meaningful and sometimes dominant share of miner revenue today. Whether fees will be consistently sufficient over the very long run is genuinely debated, but it is not a scenario where mining suddenly stops on a fixed date.[1]
Go deeper
Security in proof of work comes from the cost of acquiring enough hash power to attack the chain being higher than the expected reward. If total miner revenue (fees) were to fall a lot relative to the value being secured, in theory it could become cheaper for an attacker to acquire majority hash power, though this depends on many variables including the value of an attack versus honest mining income.
Possible offsetting factors debated by researchers and developers include: rising fees during periods of block-space scarcity, an expanding user base and layer-2 settlement demand generating steady base-layer fee revenue, and the fact that mining hardware efficiency and electricity cost trends also shape how much hash rate a given fee revenue can sustain. No one, including Bitcoin's original author, has offered a guaranteed answer, and this remains an open long-term question rather than a settled prediction.
Quick check
Answer every question correctly (100%) to complete this lesson.
1.Around what year does the Bitcoin block subsidy round down to zero?
2.What is the genuinely open question about the post-subsidy era?
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Extra exam questions
Every question here counts towards your accuracy, XP and rank. No guessing: every answer is explained.
Quick check
Answer every question correctly (100%) to complete this lesson.
1.After all 21 million bitcoin are issued, what will fund mining security?
2.Is it certain that transaction fees alone will be sufficient to secure the network long-term?
3.What is the term for the concern about long-term mining incentives after subsidies end?
4.When is the last new bitcoin expected to be mined?
5.What could happen if transaction fee revenue turns out to be too low to secure the network?
6.Does increased on-chain transaction volume necessarily solve the security budget question?
7.What role do halvings play in the approach to the fee-only era?
8.Is the fee-only security question something Bitcoin's designers explicitly acknowledged?
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Sources
- Bitcoin: A Peer-to-Peer Electronic Cash System (2008), Satoshi Nakamoto
The original nine-page proposal. Describes proof of work, timestamping and the incentive model.
- Bitcoin Core documentation, Bitcoin Core project
Reference implementation documentation, including validation and release notes.