# Bitcoin timelocks: absolute dates and relative waiting periods A Bitcoin timelock restricts when a transaction or spending path can be valid. Absolute locks refer to a block height or time condition; relative locks depend on an input’s confirmation age. Reaching the condition permits an otherwise valid spend—it does not automatically broadcast, sign or confirm a payment. Evidence: [OP_CHECKLOCKTIMEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0065.mediawiki); [Relative lock-time using consensus-enforced sequence numbers](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0068.mediawiki); [CHECKSEQUENCEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0112.mediawiki) Canonical: https://degreesofsatoshi.com/encyclopedia/bitcoin-timelocks/ Published: 2026-10-02 Substantively modified: 2026-10-02 Independently verified by an automated reviewer: 2026-10-02T18:15:23.891Z Data current through: 2026-10-02 AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied. ## Key facts - **Absolute:** CHECKLOCKTIMEVERIFY can enforce an absolute transaction locktime condition. ([OP_CHECKLOCKTIMEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0065.mediawiki)) - **Relative:** Sequence-based locks can measure block age or time in 512-second units. ([Relative lock-time using consensus-enforced sequence numbers](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0068.mediawiki)) - **Script path:** CHECKSEQUENCEVERIFY can require a relative-lock condition in a script. ([CHECKSEQUENCEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0112.mediawiki)) ## A date-like condition versus an elapsed-age condition An absolute height condition refers to the same chain height regardless of when the output was created. A relative block lock starts from the confirmation height of the particular output being spent. For example, a relative delay of 144 blocks is about confirmation age, not a guaranteed 24-hour wall-clock wait. Block intervals vary, and time-based rules use specified chain-time measurements. Evidence: [OP_CHECKLOCKTIMEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0065.mediawiki); [Relative lock-time using consensus-enforced sequence numbers](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0068.mediawiki) ## Unlocking time is not spending authority A script can combine a timing condition with a signature requirement or provide several spending branches. Reaching one branch’s time threshold does not eliminate the other requirements of that branch. A wallet-local “locked coin” setting is different: it can exclude a coin from automatic selection without imposing a consensus restriction on other holders of the signing keys. Evidence: [OP_CHECKLOCKTIMEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0065.mediawiki); [CHECKSEQUENCEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0112.mediawiki); [lockunspent RPC](https://bitcoincore.org/en/doc/29.0.0/rpc/wallet/lockunspent/) ## Budget for the transaction that comes afterward After a valid spending path becomes available, someone still needs to construct and submit the transaction and pay its fee. Inclusion depends on the network and miner selection. Read the exact script and locktime semantics rather than treating a countdown in an interface as a promise of immediate delivery. Evidence: [Relative lock-time using consensus-enforced sequence numbers](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0068.mediawiki); [Bitcoin Developer Guide: Transactions](https://developer.bitcoin.org/devguide/transactions.html) ## Questions ### Can a timelock send funds automatically on a calendar date? A timelock alone cannot initiate a payment. It changes validity conditions; an authorized party still has to create and submit a valid spending transaction. Evidence: [OP_CHECKLOCKTIMEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0065.mediawiki); [CHECKSEQUENCEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0112.mediawiki) ## Claims and scope ### bitcoin-timelocks-quick-answer A Bitcoin timelock restricts when a transaction or spending path can be valid. Absolute locks refer to a block height or time condition; relative locks depend on an input’s confirmation age. Reaching the condition permits an otherwise valid spend—it does not automatically broadcast, sign or confirm a payment. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ### bitcoin-timelocks-fact-absolute Absolute: CHECKLOCKTIMEVERIFY can enforce an absolute transaction locktime condition. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ### bitcoin-timelocks-fact-relative Relative: Sequence-based locks can measure block age or time in 512-second units. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ### bitcoin-timelocks-fact-script-path Script path: CHECKSEQUENCEVERIFY can require a relative-lock condition in a script. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ## Sources - [OP_CHECKLOCKTIMEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0065.mediawiki) — Bitcoin BIPs contributors. Absolute locktime constraints for spending transaction outputs. Locator: Summary; Specification. Retrieved: 2026-10-02T17:22:20.600Z. - [Relative lock-time using consensus-enforced sequence numbers](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0068.mediawiki) — Bitcoin BIPs contributors. Sequence-based relative confirmation age constraints. Locator: Specification. Retrieved: 2026-10-02T17:22:20.762Z. - [CHECKSEQUENCEVERIFY](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0112.mediawiki) — Bitcoin BIPs contributors. Script enforcement of relative lock-time constraints. Locator: Summary; Specification. Retrieved: 2026-10-02T17:22:20.748Z. - [lockunspent RPC](https://bitcoincore.org/en/doc/29.0.0/rpc/wallet/lockunspent/) — Bitcoin Core. Preventing specified wallet outputs from automatic coin selection. Locator: Arguments and result fields. Retrieved: 2026-10-02T17:03:41.086Z. - [Bitcoin Developer Guide: Transactions](https://developer.bitcoin.org/devguide/transactions.html) — Bitcoin developer documentation contributors. UTXO inputs, transaction outputs, change and the difference paid as a fee. Locator: P2PKH Script Validation; Transaction Fees And Change. Retrieved: 2026-10-02T17:03:41.190Z. ## Revision history - 2026-10-02: Initial Bitcoin encyclopedia entry at this permanent URL. - 2026-10-02: Added reusable claims, explicit source locators, and matching Markdown and JSON. This publishing change does not itself establish factual verification. ## Cite this entry Degrees of Satoshi editorial project. “Bitcoin timelocks: absolute dates and relative waiting periods.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/bitcoin-timelocks/