Documentation
A permanent minimum reward (tail emission) — material for a decision
Status: in the code as the parameter TailSubsidy = 0.999 POWM; final confirmation before the
mainnet genesis
Context: fees, dust and the utxo set — the fees are meant to stay cheap, like on BSC. Cheap fees are only
sustainable when miners have an income from elsewhere.
The problem
Subsidy() in internal/chain/subsidy.go: 40 POWM, halving every 1,050,000 blocks (~4 years), zero
after 63 halvings. There is no permanent reward in the code. The fees from a full block at the bottom
rate are ~0.0026 POWM — today 0.007 % of a miner’s income, in 32 years 1.6 %. When the reward falls
and the fees stay tiny, the miners leave and a 51 % attack gets cheaper.
Bitcoin: since the 2024 halving the fees have been permanently under 1 % of miners’ income (around 0.5 % at the end of 2025).
How others solve it
| coin | the model | the numbers |
|---|---|---|
| Monero | a permanent reward of 0.6 XMR/block since June 2022, 2 min blocks | ~0.9 % a year at the start, falling over time |
| Dogecoin | a fixed 10,000 DOGE/block since 2014, 1 min blocks, no cap | ~5 bn/year, ~3.4 % (2026), falling |
| Grin | 1 GRIN per second forever, no halving | under 10 % after 10 years, under 5 % after 20 |
| Ergo | the emission ends; “storage rent” — a miner may take ~0.14 ERG from coins untouched for 4 years | no inflation, inactive coins pay |
| Bitcoin | none, it relies on fees | the fees are < 1 % of income |
Our options (simulated exactly per Subsidy())
| tail reward | supply in 20 y | in 40 y | in 60 y | inflation in 32 y | reward/block in 40 y |
|---|---|---|---|---|---|
| none (today) | 81.3 M | 83.8 M | 83.9 M | 0.10 % | 0.039 POWM |
| 0.6 POWM | 81.3 M | 85.1 M | 88.3 M | 0.19 % | 0.6 POWM |
| 1.25 POWM | 81.3 M | 87.9 M | 94.4 M | 0.39 % | 1.25 POWM |
| 2.5 POWM | 81.3 M | 94.4 M | 107.6 M | 0.74 % | 2.5 POWM |
The first 20 years are identical for every option — the tail reward only kicks in where halving would drop below it.
The chosen value: 0.999 POWM
The sum of the ASCII codes of the letters in “PowMachina” is 999. A tail reward of 0.999 POWM: the reward halves five times down to 1.25 POWM, and at the sixth halving (~year 24) it drops to 0.999 instead of 0.625 and stays there. The inflation is ~0.3 % and falling, and in 40 years the supply is ~87 M POWM. Final confirmation before mainnet (the proposal: the community during the testnet); in the code as a network parameter.
The original recommendation: 1.25 POWM
- No jump: 1.25 POWM is exactly the reward after the fifth halving (~year 20). The rule can be said in one sentence: “The reward halves five times and then stays at 1.25 POWM forever.”
- Inflation of ~0.4 % and falling — below the growth of gold reserves (~1.5–2 % a year), half of Monero’s.
- It fits the project’s philosophy: mining for everyone, cheap fees forever — miners always have something to live on without the fees having to be raised.
- The cost: the 84 M cap falls. In marketing terms “84 M” → “a reward for miners forever”.
I do not recommend storage rent (Ergo) as the main model: somebody with a cold wallet would have to move their coins every 4 years or slowly lose them — that is not “simple for people”. It is interesting as a supplement to UTXO protection (it cleans up dust and lost coins), but that is a separate question.
Why now
The emission is consensus. Monero had a tail reward in the plan from the start (2014); Bitcoin
cannot add one, because it would be a hard fork and a social fight. The change in the code is small:
in Subsidy(), max(base, tail) from the height where base would fall below tail, plus the
emission tests and an adjustment of MaxSupply (today the cap on checking outputs) and the
documents.