Coin control is an advanced feature in the BitBoxApp that lets you manually choose which bitcoin coins, also called UTXOs (Unspent Transaction Outputs), you want to spend when creating a transaction.
Normally, the BitBoxApp selects coins automatically. For most transactions, this is the easiest and recommended option. If you want more control over privacy, wallet organization, and transaction handling, you can enable coin control and choose specific UTXOs yourself.
You may want to use coin control if you want to:
- keep funds from different sources separate
- consolidate small UTXOs
- spend specific coins only
- better understand how your bitcoin wallet works
Before you start
- Coin control is an advanced feature. If you are new to Bitcoin, you can still use it safely, but it helps to understand the basics of UTXOs first. For a deeper explanation, see What is a UTXO?.
- For most users, the default automatic coin selection remains the easiest option.
How to enable coin control
To use Coin Control, you first need to enable it in the BitBoxApp settings.
- Open the BitBoxApp.
- Click Settings in the bottom-left corner.
- Open Advanced settings.
- Find Enable coin control.
- Turn the toggle on.
Once enabled, the feature becomes available on the send screen of your Bitcoin account.
Don’t see the feature?
Coin control is only visible while preparing a bitcoin transaction. You will not see it directly in the account overview or settings after enabling it.
To open the coin control panel and view your UTXOs, you do not need to enter a recipient address or an amount. If the Remember Wallet (watch-only) feature is enabled and you only want to view your UTXOs, connecting the BitBox02 hardware wallet is not required.
How to find and use coin control in the BitBoxApp
After enabling the feature, coin control appears when you create a bitcoin transaction.
Open the coin control panel
- Open the BitBoxApp.
- If the watch-only feature Remember Wallet is not enabled, connect your BitBox02 and unlock it.
- In the left sidebar, select the account you want to send from, then click Send.
- Click coin control to open the coin selection panel.
You will then see a list of available UTXOs that you can manually select for the transaction.
Select your coins
In the coin control panel, you can see your available UTXOs and related information, such as:
- label or note, if available
- BTC amount
- fiat value
- date
- receiving address
- outpoint
Select one or more UTXOs by clicking the checkbox next to them.
Review labels carefully
If your wallet contains coins from different sources, labels can help you avoid spending the wrong UTXOs together. See also Managing wallet labels (BIP-329).
Choose how to send
You can use coin control in two ways.
Send a specific amount
Enter the recipient address and the amount you want to send, then select enough UTXOs so their total value covers:
- the amount you want to send
- the network fee
Sending a specific amount can be useful for regular payments or for ownership proofs, such as a Satoshi Test.
If the selected coins are worth more than the amount you send, the remaining bitcoin is returned to your wallet as change.
Good to know about change
The returned change is not shown as a separate incoming transaction in the main transaction history overview of the BitBoxApp. You can see it in the coin control panel, where the corresponding UTXO is marked with the blue label Change address.
Send the full value of selected coins
You can also send the full value of the selected UTXOs, minus the transaction fee.
This is useful if you want to:
- consolidate coins
- move selected UTXOs to another wallet
- transfer selected funds without creating additional leftover UTXOs from other inputs
Finalize the transaction
- Review the transaction summary in the BitBoxApp.
- Verify the recipient address, amount, and fee on your BitBox02 screen.
- Confirm the transaction on the device.
UTXO selection is permanent once spent
Once a transaction is confirmed, the selected inputs become linked on the blockchain. Always review which UTXOs you are combining before sending.
Why use coin control?
Coin control is especially useful if you want more precision over how your bitcoin is spent.
Improve privacy
When you spend multiple UTXOs in one transaction, they become linked on the public blockchain. Coin control helps you avoid combining coins from different sources unnecessarily.
For example, you may want to keep:
- coins received from an exchange
- coins received privately
- coins related to different use cases
separate from one another.
Prove ownership of funds
Some services may ask you to prove that you control a specific address by sending a small transaction from it. Coin control can help you choose the relevant UTXO for that purpose.
See also How to perform a Satoshi Test.
Consolidate small UTXOs
Over time, your wallet may collect many small UTXOs. Coin control allows you to combine them into fewer, larger UTXOs.
This is often called UTXO consolidation. It can make wallet management easier and may help reduce future transaction fees.
To learn more, see What is UTXO consolidation?.
Best practices when using coin control
Label your transactions
Labels make coin control much easier to use because they help identify where funds came from.
Useful examples include:
- From Kraken
- Salary payment 09/2025
- Payment from client
- Private purchase
You can add notes to transactions in the BitBoxApp transaction details. For more information, see Managing wallet labels (BIP-329).
Avoid unnecessary address reuse
For better privacy, it is recommended to use a new receiving address for each incoming payment.
If an address has been reused, the BitBoxApp may show an Address re-used tag in the coin control panel.
Address reuse is not ideal for privacy because it makes it easier to link multiple transactions together. In some cases, such as exchange whitelisting, it may still be necessary.
Understand change outputs
If the selected UTXOs are worth more than the amount you send, the remainder is returned to your wallet as a new change UTXO.
You can think of UTXOs like individual banknotes and coins in a physical wallet. If you need to pay for something that costs $12, you might use a $10 bill and two $1 bills. Your Bitcoin wallet does the same thing, combining different UTXOs to make a payment.
It can be helpful to keep this in mind when reviewing future transactions and labels.
Frequently Asked Questions
I enabled coin control, but I still can’t see it. Where is it?
Coin control only appears while preparing a bitcoin transaction. Open a Bitcoin account, click Send, and then open the coin control option from the send screen.
Can I disable coin control again?
Yes. Go back to Settings > Advanced settings and turn off Enable coin control.
What happens if I don’t select enough coins?
The BitBoxApp will not let you continue until the selected UTXOs cover both the amount you want to send and the network fee
What happens if I click on “Send all” without using coin control?
When coin control is not active, the checkbox on the send screen is labeled Send all. Ticking this box creates a transaction that sends the entire balance of that account to the recipient you entered. The BitBoxApp will automatically select all the necessary coins (UTXOs) to do this.
Do I need to choose a change address manually?
No. The BitBoxApp handles change automatically and sends the remainder back to your wallet if needed.
What does the “Address re-used” tag mean?
It means that the address linked to that UTXO has been used more than once. This is a privacy warning, because reused addresses make transaction history easier to connect.
What happens if I accidentally mix UTXOs from different sources?
Once the transaction is confirmed, those UTXOs become linked on the blockchain. This can reduce privacy and make those funds easier to analyze together later.
Can I view my UTXOs without connecting my BitBox02?
Yes, if Remember Wallet (watch-only) is enabled. In that case, you can open the coin control panel and view your available UTXOs without connecting the BitBox02. To sign and send a transaction, you still need the device.