TL;DR
Keep business bitcoin in its own vault, separate from personal coins, even if the same devices sign both. Decide who holds which key, give your accountant a watch-only view, and make sure the company can reach the coins if you can’t.
Separate vault, same devices
You don’t need extra hardware. The same three devices can hold a second multisig by using a different account number in the derivation path (1 instead of 0). Build and test one vault completely before starting the other, and keep two wallet files with clear names.
Who holds the keys
- One owner: you hold all three keys, as in the guide. Simple, but the company depends entirely on you.
- Two partners: each holds one key. The third goes to someone neutral, such as the company’s lawyer or accountant, who only hands it over when both partners ask. No one can move funds alone.
- Larger teams: consider 3-of-5: the company can lose two keys, and no two people can move funds together.
Watch-only for bookkeeping
Your accountant can import the business vault’s descriptor into Sparrow as a watch-only wallet and see every transaction and balance. They can’t move anything, but they’ll see every future address too, and you can’t take that back. Give it only to someone you’d trust with your bank statements, and only for the business vault.
Continuity
Personal bitcoin passes to your heirs; company bitcoin belongs to the company. Write down, for whoever takes over, what the company holds, where the backups are and how to recover. Keep it with the company’s other succession documents, not only in your personal inheritance letter.
Records
- Keep a log of every deposit and withdrawal with its purpose.
- Label transactions in Sparrow and export the labels now and then.
- Ask your accountant how your country treats bitcoin on the balance sheet.
This isn’t legal or tax advice. Rules differ by country and company type.