UTXO Dust

Overview

In Bitcoin, nodes use relay-policy calculations to discourage outputs below an estimated economic threshold. The threshold is not one universal fixed number because different script types require different future input sizes and fee assumptions.

Dust creates operational problems for wallets and businesses. It increases UTXO count, enlarges future transactions, complicates reconciliation, and can make the wallet balance appear more usable than it really is. Services may set minimum deposit or withdrawal amounts to avoid creating uneconomic outputs.

Attackers can send tiny amounts to many addresses. If a wallet later combines the dust with other UTXOs, analysts may infer common ownership. Wallets can mark suspicious outputs and exclude them from automatic coin selection, although the public ledger record remains.

Consolidating dust during very low fee periods can recover some value, but it may reduce privacy and still be uneconomic. The wallet should compare the cost of spending each output with its value and future fee expectations.

Applications should distinguish dust from underpayment. A small transaction can be economically valid yet fail to meet an invoice amount. UTXO dust is specifically an output-level cost and state issue, not merely any low-value payment.

Dust policy should remain separate from wallet display policy. A wallet may hide tiny outputs from the spendable balance while still tracking them for security and audit. Services should avoid automatically returning dust because the sender address may belong to an exchange or attacker. Recording the output without crediting a payment often provides the safest operational response. Wallet policy should remain transparent to users.