# Sweeping ### What is Sweeping? Sweeping is an accounting optimization for tracking Bitcoin deposits in tBTC contracts. It involves periodically consolidating recent Bitcoin deposits into a single Unspent Transaction Output (UTXO) for a more optimal commitment cadence to Ethereum. This process simplifies tracking associated public keys and refund time locks while also helping prevent supply peg disruption. Typically, Sweeping runs every 8 hours, depending on the volume and size of deposits. ### How it works When a user makes a deposit, they lock the funds using our [locking script](https://blog.threshold.network/tbtcv2-deposits-explained/). This creates an Unspent Transaction Output ([UTXO](https://learnmeabitcoin.com/technical/utxo)). Typically, the job of a bitcoin "wallet" (wallets don't exist in the same way they do on Ethereum) is to scan the blockchain for specific locking script patterns it thinks it can unlock (like a [P2PKH script](https://learnmeabitcoin.com/technical/p2pkh) associated with your public key) and sum up the relevant funds. When you want to send someone else bitcoin, the wallet software figures out which UTXOs to unlock to send to them so that you don't have to. If we wanted to be able to redeem bitcoin deposits, we would need to track which deposits are associated with which public keys, the same way that wallet software does; this is a headache, especially from a bitcoin mining fee perspective. Further, our [locking script](https://blog.threshold.network/tbtcv2-deposits-explained/) includes this idea of a time-locked refund. If the funds are not touched by a certain amount of time (9 months at the time of writing; `` In the script, we allow the depositor to reclaim their deposit. We do this as an effective escape hatch in case something goes wrong with the protocol or deposit. As a result, we set the same time limit for collecting the deposit. If we don't move the funds by that time, a user could deposit 5 BTC, receive 5 TBTC, and then 9 months later reclaim their original 5 BTC without redeeming the 5 BTC. This would break the TBTC supply peg. Sweeping aims to solve both of these problems simultaneously, as well as serves as a performance optimization. Every 8 hours, we collect all recent deposits, unlock them, and then send the funds using a standard P2PKH script back to the wallet, consolidating the UTXOs into a single UTXO. The result is that all of the scattered deposits are "swept" into a single "pile" represented by one UTXO that we can commit to on Ethereum. ### Example Here's a deposit for [10.3 BTC](https://mempool.space/tx/a4dc393dc48a82d1bb2d5dc30437fdb83e61565c47274dbe1c064117541ea97d). That deposit is swept in transaction [0db1929c2fa41649264b95b9162bc7a12f43cb455a91bae7177667a53290d7e8](https://mempool.space/tx/0db1929c2fa41649264b95b9162bc7a12f43cb455a91bae7177667a53290d7e8) (along with many other deposits). That was one of three sweeps performed by that wallet (as of writing). ![https://mempool.space/tx/1ddffd9e5d4c84b49c9f912bfc3b97d8f5aba0620e35ec6a50e7043c9141d373](/files/2PlpiOLWM3pOv9H3GC6c) That transaction created a UTXO worth 1.51614471 BTC. The next transaction ![https://mempool.space/tx/40240aaa602f534ae7e1654546e7ee5f49a32d6d64215d90acbb9a720f63098e](/files/Z7mFaIiuA8OliTNtXTao) Used the old UTXO (the first input) as well as all of the recent deposits to create a new UTXO (the output on the right) worth 15.42475511 BTC. The final transaction ![https://mempool.space/tx/0db1929c2fa41649264b95b9162bc7a12f43cb455a91bae7177667a53290d7e8](/files/Qs07DPxt5FBdpPV1MpcQ) Follows the same pattern. It uses the old UTXO (the first input) and the recent deposits to create a new UTXO worth 59.52818486 BTC. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.threshold.network/tbtc-v2/sweeping.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.