Tail emission is a permanent floor under a block reward. After the decaying part of the schedule finishes, the protocol keeps issuing a small constant amount forever instead of stopping. Monero is the reference implementation: its rewards fell until tail emission began at the end of May 2022 and now hold at 0.6 XMR per block or less. The consequences are deliberate. There is no supply cap, and there is no date on which security stops being paid for.
A tail emission trades a hard cap for a security budget that never runs out. Whether that is a good trade depends entirely on whether a fee market alone can pay for block production, and no chain has yet operated long enough without a subsidy to answer that.
The rule, and the reason Monero gives for it
Monero states it without hedging: block rewards will never drop to zero. Rewards declined until tail emission commenced at the end of May 2022, at which point they hold fixed at 0.6 XMR per block or less, the qualifier covering block size penalties.1
The stated rationale is about incentives rather than supply. Monero's documentation argues that miners need an incentive to mine, that its dynamic block size drives fee competition downward, and that if mining stops being profitable miners leave and network security falls. In that framing, tail emission is what allows a dynamic block size and a fee market to develop in the first place.1
The opposite bet from a hard cap
Bitcoin's design answers the same question the other way. Its subsidy halves at a fixed block interval, and blocks at a height of 6,930,000 or above receive no subsidy at all.2 Fees become the entire payment for block production. Our halving entry covers that schedule; the point here is that these are two answers to one question and they disagree.
Neither answer has been tested at its terminal state. Bitcoin has never run a year without a subsidy, and Monero's floor has only been live since 2022. Anyone presenting either as settled is stating a preference.
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The argument the floor rests on
Carlsten, Kalodner, Weinberg and Narayanan, at ACM CCS in 2016, modelled mining under fee-only rewards and found the incentives break in specific ways: intermittent mining as operators chase profitable moments, an incentive to fork the chain in order to capture an unusually rich block, and selfish mining becoming profitable at lower hash rate thresholds than under a subsidy.3
A constant subsidy floor is a direct response to that result. It puts a predictable, non-lumpy base under miner revenue, so the behaviour the paper describes has less to work with. That is the case, and it is a case from a model published in 2016. Stating it that way is more defensible than treating a reasonable position as a proven one.
What a floor costs
It costs the cap. There is no maximum supply in a tail emission design and there never will be, so any marketing built on scarcity has to be dropped rather than reworded. Projects that choose this shape and then keep the scarcity language are creating a contradiction a reader will find.
The dilution itself shrinks over time without ever ending, because a constant issuance divided by a growing supply is a falling percentage that approaches zero asymptotically. How quickly it stops being a meaningful figure is straightforward arithmetic on your own parameters, and it belongs in your documentation as a table rather than as a reassurance.
When a floor is the right call
The test we apply is whether fee revenue is plausibly large, steady and independent of the subsidy. If block space is genuinely scarce and demanded for its own reasons, a terminal zero is defensible. If fee revenue is thin or seasonal, a floor is insurance against a failure mode with no cheap fix once it has started.
Size the floor against the security you are trying to buy rather than against a figure that looks small in a table, and state in the documentation that the supply is uncapped, in those words. A design that hides its own mechanism from the people relying on it fails for reasons that have nothing to do with the mechanism.
Common questions
What is tail emission in crypto?
Tail emission is a permanent block reward that never stops. After the decaying part of a schedule finishes, the protocol keeps issuing a small fixed amount every block instead of dropping to zero. Monero implements it: rewards fell until tail emission started at the end of May 2022 and now hold at 0.6 XMR per block or less.1 The trade is a security budget that never runs out, in exchange for an uncapped supply.
Does tail emission make a token inflationary forever?
It makes the supply grow forever, but the percentage rate falls continuously. A constant issuance divided by a growing supply is a shrinking share, approaching zero without reaching it. So a tail emission design has no maximum supply and no permanent inflation rate either. It has a permanent absolute issuance and a percentage that becomes small enough to stop being the interesting number.
Why does Monero have tail emission but Bitcoin does not?
They answer the security budget question differently. Monero argues that miners need an ongoing incentive and that its dynamic block size pushes fees down, so a permanent floor is what lets a fee market develop safely.1 Bitcoin's rule ends the subsidy entirely above block height 6,930,000 and relies on fees alone.2 Both are coherent designs, and neither has yet operated in its terminal state.
See Tokenomics Audit for how this applies in practice.
Sources
- Moneropedia: Tail Emission
The Monero Project (getmonero.org), current
States that Monero block rewards will never drop to zero, that tail emission commenced at the end of May 2022, that rewards stay fixed at 0.6 XMR or less per block, and gives the miner-incentive rationale. - Bitcoin Developer Reference: Block Chain, block subsidy and halving
bitcoin.org / Bitcoin Core developer documentation, current
States that the subsidy started at 50 bitcoins, halves every 210,000 blocks, and that only blocks below height 6,930,000 are entitled to a subsidy at all. - On the Instability of Bitcoin Without the Block Reward
Carlsten, Kalodner, Weinberg and Narayanan, ACM CCS 2016 (author copy, Princeton University), 2016
Formal analysis of mining incentives under transaction fees alone, finding intermittent mining, forking to capture high-fee blocks, and selfish mining profitable at lower hash rate thresholds.
Last reviewed 2026-08
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