The short answer
- Use one account for business income and business costs. It does not have to be a formal business account at the start, but it must be used for nothing else.
- Pay yourself by a dated transfer to your personal account, with the same description every time. That transfer is your pay, and it is the only line that crosses.
- Decide a rule for anything shared - phone, internet, a room at home - and apply the same percentage each month.
- Keep receipts in one place with the date in the filename, so a month can be reconstructed without your memory.
- Reconcile once a month against the statement, not against how the month felt.
Setting it up in an afternoon
- Open or nominate the account. Move every existing business subscription onto it.
- List your business costs from the last three statements and mark which are shared with personal use.
- Choose the shared percentage once and write down why, so you are not re-deciding it every month.
- Set a pay day. Transfer a fixed amount on that date even in a good month; leave the surplus in the business.
- Put a twenty-minute monthly review in the calendar with a start date.
The two mistakes that undo it
The first is the small exception: one personal coffee on the business card, then another. Within a quarter the account is mixed again and the separation is decorative. If you need personal money, transfer it as pay and spend it from the personal side.
The second is treating the whole balance as yours. Money sitting in the business account includes tax you have not paid yet and costs you have already committed to. Paying yourself a fixed amount rather than whatever is there is what keeps those two facts from colliding.
What this makes possible
- You can say what the business earned last month in one sentence, from one number.
- Tax time becomes a filter rather than an archaeology project.
- A quiet month is visible early, because the pay transfer starts to hurt before the balance runs out.
The free tool for this
The 50 / 30 / 20 split, on your own numbers - The 50 / 30 / 20 split, on your own numbers. It runs in the page, asks for your own numbers, and sends nothing anywhere.
If you would rather not build it yourself
Money OS runs this as a conversation: you describe the month, it keeps the categories, the shared-cost rule and the running totals, so the review is twenty minutes rather than a weekend. Claude Code Workflows for Personal Finance - 8 Commands + Ledgers (Money OS) is $34. See it on the shop, and there is a plain page about it here: what it holds.
Questions people actually ask
Do I legally need a separate business account?
That depends on where you trade and how you are registered, so check your own rules. Separation is worth doing regardless, because it is the only way to read your own numbers.
What if a client pays into my personal account?
Transfer it to the business account the same day with a dated note, and record it as business income. Fix the payment details for next time.
Read next
How to categorize a bank statement without losing a weekend, How to find every subscription you forgot you had, The quarterly taxes checklist for a one-person business, What to check in a twenty-minute monthly money review.