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Key Takeaways
- Peter Todd wants a permanent tail emission to protect Bitcoin’s long-term miner security.
- The proposal would break Bitcoin’s 21 million cap and require a contentious hard fork.
- Adam Back and Pierre Rochard argue fees can secure Bitcoin without permanent inflation.
Bitcoin crossed 20 million BTC mined in March 2026, leaving less than one million coins to be issued over roughly the next 114 years. More than 95% of the supply Bitcoin is ever supposed to have is already onchain.
Yet one of Bitcoin’s longest-running developers is asking whether the last part of that sentence should remain true forever.
Peter Todd, the longtime Bitcoin contributor behind OpenTimestamps, revived his case for tail emission at Bitcoin++ Toronto on July 23. The conference released the recording on Aug. 14, setting off another argument over Bitcoin’s 21 million supply cap. Todd’s proposal would preserve a small block subsidy indefinitely instead of eventually allowing newly issued BTC to fall to zero.
Bitcoin’s 21 million supply cap is being debated again.
Core developer Peter Todd argues Bitcoin could eventually use tail emissions — a small permanent block reward — to support miner security, similar to gold’s ongoing supply growth.
The idea is controversial, but the 21… pic.twitter.com/094bnTqIv3
— CryptosRus (@CryptosR_Us) August 17, 2026
It sounds almost incompatible with Bitcoin’s pitch: a cryptocurrency valued partly because nobody can print more than 21 million units.
Todd’s argument starts somewhere else. He is asking who pays miners when Bitcoin stops printing coins.
Peter Todd’s proposal is about Bitcoin’s security budget
Bitcoin miners currently earn money from two sources: newly issued BTC and transaction fees.
The first source is deliberately disappearing.
As of Aug. 20, the block subsidy is 3.125 BTC. It falls to 1.5625 BTC at the next halving, expected in 2028, and continues halving roughly every four years until issuance effectively reaches zero around 2140.
Fees are nowhere close to replacing it today.
MARA Holdings, one of the world’s largest public Bitcoin miners, reported that transaction fees represented only 0.7% of its total Bitcoin mining rewards in the second quarter of 2026, down from 1.4% a year earlier. Recent network data have shown a similar picture: during one early-August week, miners received 3,275 BTC from subsidies and just 26.38 BTC from transaction fees.
Todd sees a potential problem in assuming that a fee market which currently supplies less than 1% of miner revenue will eventually replace almost all of it.
His concern is not simply that miners will earn less. A fee-only system changes how miners are paid.
A fixed block subsidy gives every newly mined block a predictable base reward. Transaction fees can be highly uneven. One block may contain relatively little fee revenue while another contains a much larger pool.
That issue has academic backing. In 2016, Princeton researchers Miles Carlsten, Harry Kalodner, Arvind Narayanan and Matthew Weinberg modeled Bitcoin without a block reward. They found that fee-only mining could create incentives to reorganize particularly valuable blocks and could make certain selfish-mining strategies profitable at far lower levels of hash power.
Todd has repeatedly cited that research. In his 2022 paper on tail emission, he noted that no major proof-of-work cryptocurrency had yet demonstrated long-term operation funded exclusively by transaction fees.
Tail emission would break the 21 million Bitcoin cap
Todd’s proposed fix is conceptually simple: never let Bitcoin’s block subsidy completely disappear.
Instead, miners would eventually receive a small, fixed amount of newly created BTC per block forever.
Monero already does this. Its main issuance schedule ended in 2022, after which the network began paying miners a permanent 0.6 XMR per block. Because the number of newly created XMR remains fixed while the existing supply grows, Monero’s percentage inflation rate continually declines toward zero.
Monero developer Peter Todd wants to add a small permanent issuance to Bitcoin.
His argument deserves better than the replies it's getting, so here it is straight. Coins are lost forever when keys are lost. A tiny permanent issuance would roughly offset those losses, so the… pic.twitter.com/vsHjNvUcy7
— Bitcoin Well (@bitcoinwell) August 17, 2026
Doing the same to Bitcoin would mean more than 21 million BTC eventually existed.
Todd does not deny that.
In a 2022 Bitcoin developer mailing-list exchange, he went further, arguing that if Bitcoin eventually became unstable without a subsidy, the market could choose to redefine Bitcoin and remove the 21 million limit.
His economic argument rests heavily on lost Bitcoin.
Coins disappear from usable circulation when owners lose keys, die without transferring access or permanently destroy funds. Estimates vary widely, precisely because an unmoved Bitcoin cannot be reliably distinguished from a lost one.
Todd’s model treats those losses as a continuous leakage from circulating supply. If miners continuously create coins while holders continuously lose coins, he argues, effective supply can eventually approach an equilibrium rather than grow without limit.
Todd has previously floated an annual rate around 0.1% as an example rather than a formal proposal. In a 2022 discussion, he argued that 0.1% annual dilution compounded over 75 years would amount to roughly an 8% change, small compared with Bitcoin’s historical price volatility.
That is far less aggressive than a separate proposal made in July by StarkWare CEO Eli Ben-Sasson, who suggested replacing Bitcoin’s fixed cap with maximum annual issuance of as much as 4%. Ben-Sasson also cited permanently lost private keys and long-term mining security.
Todd and Ben-Sasson should not be treated as proposing the same monetary policy. Todd’s tail-emission argument is built around a small permanent mining subsidy; Ben-Sasson’s 4% ceiling would allow vastly larger issuance.
Adam Back says the security argument does not justify inflation
The backlash has been immediate.
Adam Back, Blockstream CEO and inventor of Hashcash, rejected the latest attempt to revive the debate. Responding after Todd’s Bitcoin++ talk resurfaced, Back warned against using simplified narratives to rally users behind what he called a “dangerously inadvisable cause.”
A more technical counterargument has come from Pierre Rochard, former Riot Platforms research executive and CEO of The Bitcoin Bond Company.
Bitcoin is decentralized, it can’t be captured by special interests.
— Pierre Rochard (@BitcoinPierre) August 16, 2026
https://x.com/BitcoinPierre/status/2089003977052766274
Rochard rejects the premise that Bitcoin requires a permanently predetermined “security budget.” He argues that full nodes enforce rules such as the 21 million cap, while miners provide settlement finality by making reorganizations costly.
His model assumes the fee market becomes responsive when security is actually challenged. If block space becomes scarce or a censorship attack disrupts confirmations, users can raise fees through mechanisms including replace-by-fee and child-pays-for-parent. Miners then have an economic incentive to abandon an attacking coalition and collect those higher public fees.
Rochard pointed to periods when fee spikes already pushed individual Bitcoin blocks above the subsidy. At 1,000 sats/vB across roughly one million virtual bytes, he calculated that fees could reach around 10 BTC in a single block.
Todd’s objection is that intermittent fee spikes are not the same as a predictable permanent reward.
Those two positions expose the real argument. It is not whether fees can become large. They demonstrably can. It is whether an unpredictable fee market can reliably support Bitcoin’s security decade after decade as subsidy revenue falls toward zero.
The 21 million cap is not something Todd can simply change
There is also a large gap between debating tail emissions and implementing them.
Todd has not submitted a formal Bitcoin Improvement Proposal to remove the supply cap. Bitcoin’s current BIP repository contains no Todd tail-emission proposal. His work so far consists of research, public arguments and conference discussions rather than an activation plan.
Permanent new issuance would require a hard fork because existing Bitcoin nodes reject blocks creating more BTC than Bitcoin’s current consensus rules permit.
Todd acknowledged that obstacle in his original paper, writing that adding tail emission would require convincing Bitcoin’s full-node community to accept an incompatible monetary rule. He also conceded that the hard fork itself could cause more damage than the security problem it was supposed to fix.
Kraken Chief Economist Thomas Perfumo made the opposite economic case when Bitcoin crossed 20 million coins in March. He argued that the cap is enforced simultaneously by thousands of nodes and that participants asked to approve additional issuance would be voting for dilution of the asset they already own.
CoinShares has reached a similar conclusion. Its analysis found that while the supply limit can technically be changed, nodes can simply refuse the new software. It also argued that miners themselves could lose economically if higher issuance damaged Bitcoin’s scarcity premium enough to reduce BTC’s dollar price.
Todd has another idea that keeps 21 million intact
Todd has also proposed a second mechanism: demurrage.
Instead of creating BTC above 21 million, the network could impose an age-based cost on coins when they are eventually spent and redirect that value toward future mining rewards.
In an earlier explanation, Todd suggested an illustrative mechanism equivalent to roughly a 0.1% annual charge, accumulated according to how long coins remained unspent. The proceeds would feed a pool miners could draw from over time.
Economically, Todd considers demurrage similar to tail emission: Bitcoin holders fund mining security either through dilution or through an explicit charge on existing coins.
Politically, demurrage may be an even harder sell. It avoids increasing nominal supply above 21 million but changes another property Bitcoin holders value heavily: the ability to hold coins indefinitely without protocol-level decay.
Bitcoin’s 21 million debate is arriving decades early
Nothing currently points to Bitcoin abandoning its cap.
More than 20 million BTC are already mined, the subsidy still pays 3.125 BTC per block, there is no tail-emission BIP, and any attempt to issue additional coins would face a hard fork among users financially incentivized to preserve scarcity.
But Todd is deliberately raising the question before Bitcoin is forced to answer it.
The next halving arrives around 2028. Another follows around 2032. Each one strips away another half of the subsidy while the network has yet to prove that transaction fees can sustainably replace it.
For Todd, 21 million is an engineering parameter that can be reconsidered if it threatens Bitcoin’s long-term operation.
For Back, Rochard and much of the Bitcoin community, changing that parameter attacks the reason Bitcoin commands value in the first place.
That leaves Bitcoin with a century-long experiment already underway: can an asset built around absolute scarcity eventually pay for its own security without compromising the scarcity that made it valuable?
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