Static Per-Output Miner Fee

Abstract

This BIP proposes a consensus-enforced per-output miner fee: a fixed satoshi amount paid permanently to the miner of each block for every newly created non-coinbase transaction output.

Bitcoin has no consensus-enforced fee floor today. Policy-based dust limits and mempool filters are unenforceable, because any transaction that pays enough miner fees can still be included by a participant who chooses not to enforce those filters. This proposal is the first consensus rule that directly prices the permanent cost of UTXO creation, and it binds every participant.

The fee is a single fixed constant. There is no dynamic component, no sampling window, no moving average, and no rate adjustment. Every non-coinbase output pays the same fee regardless of script type, value, or fee environment. The fee goes to the miner of the confirming block and is not recoverable by the sender.

The design is deliberately small. A companion BIP adds a dynamic escalation layer on top of this static fee once the network has operational experience with the base rule.

Motivation

The Problem: No Consensus Fee Floor Exists

Bitcoin has no consensus rule requiring any minimum fee for transaction inclusion. Policy filters, dust limits, and minimum relay fees can all be bypassed by routing through a miner who does not enforce them. That is why UTXO spam debates have cycled for years without resolution. Policy binds willing participants. Consensus binds everyone.

This BIP introduces a consensus fee floor scoped to UTXO creation: the surface where unpriced externalities are measurable, permanent, and harmful to network health.

The Two Spam Vectors

UTXO set spam runs on two vectors.

Two UTXO spam vectors, one permanent fee
A per-output fee closes both: every output costs the fee regardless of value, and cost scales linearly with count.

The value vector is the main historical pattern: outputs created at or near zero value that are uneconomical to spend and sit permanently in the UTXO set. They cost almost nothing to create because their value is tiny and miner fees can be spread across many outputs.

The count vector is the secondary pattern: many outputs per transaction, each carrying real value, bloating the UTXO set through volume rather than dust. This vector becomes more attractive once the value vector is closed.

A permanent per-output fee closes both at once. Any output costs the fee to create, whatever its value. The fee scales linearly with output count. There is no capital recovery path: the fee goes to miners and does not come back.

The Externalized Cost This Proposal Prices

The per-output fee is not a new tax on Bitcoin use. It prices a cost that already falls on node operators instead of the actors who create it.

Full Cost of Running a Bitcoin Node (v2.4, July 2026) estimates that burden:

UTXO set composition (May 2025, tip 892385)
■ Inscription-related ■ Other UTXOs
Inscription UTXOs
51,188,145
Mean value
811 sats
Network burden
~$4M / year
Mempool Research UTXO Set Report. Inscription outputs impose permanent storage on every node, whether or not the operator cares about that activity.
ExternalityEstimateWho pays
Non-monetary chain share12-19% (~85-140 GB of 700-750 GB)Every new node at IBD
Annual IBD from inscriptions765 GB - 1.68 TB across ~9-12k new nodesNew participants
Per-node ongoing cost$5.52-$5.54 / month (2026)~60,000 full nodes
Aggregate network burden~$4M / yearNode operators
Core development spend~$9M / year(comparison only)
Node operators absorb a non-monetary burden approaching half of total protocol development spend, with no recovery path.

That also names a natural constituency: about 60,000 node operators absorbing roughly $4 million per year in non-monetary burden. It is a large, distributed group with a direct interest in activation.

Why Determined Spammers Require a Permanent Fee

The 2023 to 2026 inscription and ordinals waves showed that determined spammers are more price-insensitive than simple models predict. Those actors paid sustained high miner fees because presence on Bitcoin itself was part of the product. Blocks ran 91 to 97% full for long stretches, and the activity continued.

A capital lockup does not change that math. An attacker facing only a minimum output value can mint outputs, lock capital, spend them back, and repeat. The per-output fee removes that path. Every spam run is permanently more expensive, with no revolving capital to fund the next one.

Minimum output value vs per-output miner fee
Permanence is the point. Lockup is a revolving door; the miner fee is not.

Provisional Static Fee Anchor

The static fee needs a principled starting point for calibration, not an arbitrary constant. The node-cost work above helps, but the derivation has to ask the right question.

The $4 million per year aggregate and the $5.52 to $5.54 per node per month figures are the ongoing cost of non-monetary data already in the chain: storage, bandwidth, and RAM that existing inscription UTXOs impose every month. That is a stock cost, not a per-new-output flow cost. You cannot divide it by new UTXO creation rates and call the result a fee.

The right question is: what lifetime cost does one newly created non-monetary UTXO impose on the network from creation forward? That cost has three parts:

  1. Permanent storage cost: about 85 to 140GB of non-monetary chain data at $0.11/GB NVMe pricing is $9 to $15 per node in sunk storage. Spread across about 51 million inscription UTXOs, that is roughly 0.1 to 0.3 sat per UTXO in storage cost per node.
  2. Ongoing monthly storage and RAM burden: $5.52 per month per node in non-monetary ongoing cost. At 60,000 nodes and 51 million inscription UTXOs, that is about 78 sats per UTXO per year across the network, or roughly 6 to 7 sats per UTXO per node-year.
  3. IBD cost on every future node that syncs the chain: 85 to 140GB of inscription data downloaded once per new node, at about 9,000 to 12,000 new nodes per year.

Summing those pieces and discounting over a reasonable UTXO lifetime at current BTC price yields a per-UTXO externalized lifetime cost around 16 to 20 sats per output. That is a cost-derived provisional anchor, not a conclusion. It rests on one methodology paper, uses several approximations, and must be checked against two independent tests: what per-output fee would have made the 2023 to 2026 inscription and ordinals waves uneconomical at historical fees, and what fee stays negligible relative to legitimate output values across historical fee regimes. If calibration shows 16 to 20 sats is too low to deter determined count-vector spam at realistic attacker budgets, the static fee will be raised and the change documented before the proposal moves forward.

Specification

Fee Rule

Every non-coinbase transaction output created in a valid block must cause the miner of that block to collect a fee of exactly static_fee satoshis, in addition to the block subsidy and all transaction fees.

active_fee = static_fee

static_fee is a consensus constant fixed at activation. It changes only by a future soft fork.

Exempt Outputs

Coinbase outputs are the only exemption. They are how the fee is collected, so charging them would be circular. All other outputs pay the fee, including OP_RETURN and provably unspendable outputs.

Coinbase Accounting

Block validity requires that the coinbase transaction output value equals the block subsidy plus all transaction fees plus all per-output fees collected in that block:

coinbase_value = block_subsidy + sum(tx_fees) + per_output_fees_total

per_output_fees_total = static_fee × count(all non-coinbase outputs in block)

Figure: Coinbase accounting after activation. Exact equality is required; underpayment orphans the block.

Validation rules:

  1. Count all outputs across all non-coinbase transactions in the block. Do not count coinbase outputs.
  2. Transactions with zero outputs contribute zero to the count.
  3. Multiply the total output count by static_fee.
  4. The coinbase output value must equal block_subsidy + sum(tx_fees) + per_output_fees_total exactly.
  5. A block where the coinbase output value does not satisfy this equation is invalid.

This is self-enforcing: miners who validate correctly will orphan blocks that undercount or omit per-output fees in the coinbase.

Activation Height

The fee rule applies to every block at or above activation_height. Blocks below activation_height are unaffected. activation_height is set by the BIP-8 or BIP-9 signaling process and is known in advance, so wallets and services have time to update fee estimation. No separate grace window is specified: the minimum one-year signaling window is enough protection for in-flight transactions, and an extra grace window adds complexity without much added safety.

Consensus State

The only consensus state this BIP requires is:

Both are deterministic from the soft fork activation parameters and need no ongoing computation.

Parameters

ParameterDescriptionProvisional value
static_feeFixed per-output fee in sats16-20 sats (pending calibration)

At the provisional band, count-vector cost scales linearly:

Outputs created@ 16 sats@ 20 sats
1,00016,000 sats20,000 sats
10,000160,000 sats200,000 sats
100,0001,600,000 sats2,000,000 sats
Permanent, non-recoverable cost per spam run. Calibration must confirm deterrence at realistic attacker budgets and negligibility for legitimate high-output use.

Activation

This BIP is meant to deploy via a soft fork using BIP-8 or BIP-9 style signaling, with a minimum activation window of one year and no mandatory lock-in fallback. Miners who do not signal are not penalized. If signaling does not reach the threshold within the window, the proposal does not activate and the process restarts with revised parameters or renewed community discussion.

Rationale

Why a Permanent Fee Rather Than a Capital Lockup

A minimum output value floor forces attackers to lock capital in each output. That capital returns when the output is spent, so the floor is a revolving cost. The per-output miner fee removes that path: those sats go to miners and do not return. Every spam run is permanently more expensive.

Why a Single Global Rate With No Script-Type Differentiation

A single constant per output is the simplest rule. Script-type differentiation would force the fee to track script classification across every output form, create edge cases at upgrade boundaries, and make the rule harder to specify cleanly. The externalized cost this fee prices is per UTXO slot, not per script type, so a uniform fee matches the cost model.

Why OP_RETURN Pays the Fee

All non-coinbase outputs pay the fee, including OP_RETURN and provably unspendable outputs. Legitimate OP_RETURN users will object: timestamping services, colored coin protocols, and apps that embed small amounts of data for non-spam purposes.

The tradeoff is accepted for two reasons. First, the motivation is the cost imposed on node operators by all non-coinbase output creation, including outputs that never enter the UTXO set. OP_RETURN outputs consume block space and impose bandwidth and storage costs on every node whether or not they are spendable. Exempting them while citing node operator burden would contradict the premise. Second, at a correctly calibrated static fee of 16 to 20 sats, the cost per OP_RETURN output is negligible for legitimate low-volume use and material only for high-volume data embedding, which is the intended effect.

Why a Static-Only Rule First

A combined static-plus-dynamic rule has more review surface, more implementation complexity, and more political attack surface than a static-only rule. The property that matters most is that a permanent, non-recoverable cost exists on every new output. That property lives entirely in the static component. The dynamic escalation layer is a long-term anti-decay mechanism that is useful but not urgent. Staging the two rules raises the odds that the core mechanism actually reaches consensus.

Miner Incentives

Miners receive per-output fees in their coinbase. They have a financial interest in including transactions that create outputs. That is not new: miners already want fee-paying transactions. The per-output fee raises the price floor on all output creation. Spammers pay miners more per output than before. The per-output cost to attackers rises whether or not aggregate spam volume falls.

Large miners who earn significant revenue from inscription-style activity may oppose this. That opposition is short-term: a fee market where monetary transactions compete on equal terms with correctly priced non-monetary use produces more durable revenue than one distorted by externalized costs.

Interaction with BIP-110

BIP-110 targets dedicated high-bandwidth data channels: OP_RETURN and Taproot envelopes. This BIP targets UTXO creation economics and charges all outputs, including OP_RETURN. The two proposals address different surfaces and reinforce each other when activated together. Coordinated activation closes the full documented surface at once. For the channel taxonomy, see The Achievable Floor and Bitcoin Is Not a Hard Drive.

Activation Game Theory

Prior soft fork proposals that use mandatory lock-in fallbacks treat non-signaling miners as attackers rather than participants with legitimate concerns. This BIP uses voluntary signaling with no mandatory lock-in. If inscription-dependent miners block signaling, that outcome documents the network's governance dynamics and strengthens the case for implementation diversity and alternative node software.

The most credible activation path is to deploy on signet and testnet, run the rule in production across Bitcoin Commons and Bitcoin Knots, publish calibrated parameters with full chain scan results, and treat miner signaling as a multi-year process. The roughly 60,000 node operators absorbing about $4 million per year in non-monetary burden are a natural, financially motivated activation coalition that spam-mitigation efforts have not usually named explicitly.

Backwards Compatibility

Existing UTXOs remain valid and spendable. Old nodes will see new blocks as valid under the soft fork. From the user's point of view there is one fee: wallets add the weight-based transaction fee and the per-output component internally and show a single total. Wallets that do not update will underestimate fees and produce transactions that enforcing nodes reject at and after the activation height. The one-year minimum signaling window gives the wallet ecosystem time to update. Updates should be done before lock-in, not merely before activation: unlike soft forks that affect only unusual transaction types, the per-output fee affects fee estimation for nearly every transaction that creates outputs. A wallet that is not updated by lock-in will start producing invalid transactions the moment the rule activates, with no warning to the user.

Lightning channel opens, CoinJoin transactions, and exchange batch payouts will pay the per-output fee for each output created. Calibration must confirm the fee is negligible relative to typical output values across historical fee regimes. Exchanges should be engaged before signaling begins.

Reference Implementation

High-level pseudocode:

STATIC_FEE = <value to be set at activation>
ACTIVATION_HEIGHT = <determined by signaling process>

def per_output_fees_for_block(block):
    if block.height < ACTIVATION_HEIGHT:
        return 0
    count = sum(len(tx.outputs) for tx in block.non_coinbase_transactions)
    return STATIC_FEE * count

def is_valid_block(block):
    expected_coinbase = (
        block_subsidy(block.height)
        + sum(tx.fee for tx in block.non_coinbase_transactions)
        + per_output_fees_for_block(block)
    )
    return block.coinbase_value == expected_coinbase

Detailed test vectors, integer arithmetic precision requirements, and treatment of edge cases (zero-output transactions, reorgs at activation height, IBD validation) will be provided in a future numbered BIP submission.

Calibration Checklist

Calibration is a hard gate. The static fee value is provisional until this checklist is satisfied.

A. Static Fee Determination (Hard Gate)

B. Collateral Damage (Must Pass)

C. Spam Efficacy

D. Consensus Edge Cases

E. Wallet and Exchange Validation

F. Exit Criteria

Security Considerations

No dynamic manipulation surface. The static fee is a constant. It has no sampling window, no moving average, and no parameter an attacker can influence through fee activity. That is the main security advantage of the static-only design.

Coinbase underpayment. A miner who fails to collect per-output fees in the coinbase produces an invalid block, orphaned by correctly validating nodes. Self-enforcing.

Clean activation boundary. The rule takes effect at activation_height with no grace window. The one-year minimum signaling window is enough for wallets and services to update before the rule applies. Transactions broadcast before activation_height that remain unconfirmed at that height must pay the per-output fee to confirm. Wallets should watch approaching activation and rebroadcast or bump fees as needed.

Private mempool arrangements. Miners accepting non-compliant transactions through private arrangements produce blocks rejected by enforcing nodes. Orphan risk limits sustained defection.

Static fee decay over time. A fixed satoshi amount becomes economically trivial as BTC price and fee levels rise over decades. That is the known limit of the static-only design and the reason for the companion dynamic escalation BIP. The static fee is not meant as a permanent final answer; it is the first layer the dynamic BIP builds on.

References

This document is licensed under the BSD 2-Clause License.