Bitcoin Core 30.0 has lowered its default minimum transaction relay feerate from 1 sat/vB to 0.1 sat/vB, opening the door for nodes to propagate significantly cheaper Bitcoin transactions. The change reduces a longstanding default policy floor without modifying Bitcoin’s consensus rules, meaning individual node operators remain free to configure their own relay requirements.
According to the official Bitcoin Core 30.0 release notes, both -minrelaytxfee and -incrementalrelayfee now default to 0.1 sat/vB, while -blockmintxfee falls to 0.001 sat/vB. These values govern node relay and miner block-template policies rather than establishing mandatory network-wide fee levels.
Lower Fees Depend on Network Adoption
The new defaults make it technically possible for transactions paying below 1 sat/vB to propagate through upgraded nodes. However, Bitcoin Core explicitly warns that low-feerate transactions are not guaranteed to propagate or confirm until enough nodes and miners adopt compatible policies.
A transaction accepted by a Bitcoin Core 30.0 node could still encounter peers running older versions or customized configurations that reject it. Mempool minimum fees can also rise dynamically when transaction volume increases. The practical reliability of 0.1 sat/vB transactions therefore depends on both network topology and current mempool conditions, not simply on the software version used by the sender.
The change also does not mean Bitcoin transactions can pay fractional satoshis. Fees remain denominated in whole satoshis, while sat/vB represents the fee divided by transaction virtual size. What Bitcoin Core 30.0 enables is a sub-1-sat/vB effective feerate, not sub-satoshi units on Bitcoin’s base layer.
Importantly, Bitcoin Core’s wallet fee settings were not lowered alongside relay policy. The release notes state that wallet feerates remain unchanged and that operators must adjust -mintxfee before creating transactions below existing wallet thresholds. Users should therefore not expect Bitcoin Core wallets to automatically begin recommending ultra-low fees after upgrading.
OP_RETURN and Legacy Wallet Policies Also Change
Bitcoin Core 30.0 also raises the default -datacarriersize setting to 100,000 bytes and permits multiple OP_RETURN data-carrier outputs in standard transactions. The change effectively removes the previous 83-byte default data-carrier restriction while remaining subject to broader transaction-size limits.
Legacy Berkeley DB wallets can no longer be created or loaded in version 30.0. Existing users must migrate those wallets to the descriptor format using the available migration tooling. The release therefore advances Bitcoin Core’s transition away from its legacy wallet architecture while preserving a defined migration path.
The October 10, 2025 release also introduced a REST endpoint for retrieving spent transaction outputs from block undo data and several networking and mempool improvements. For transaction fees, however, the central change is greater policy flexibility rather than a guaranteed new fee market, with the long-term impact depending on how broadly nodes and miners adopt the lower defaults.