From one CSV to the day you go under.

1. Hand it a CSV

Export your account's transactions from your bank as a CSV file (most banks call it Download or Export), then open Berm, create your account, and choose the file on the Import card. Three months or more is best: a monthly bill has to come round at least twice to be recognised.

Banks do not agree on what an export looks like — one amount column or separate debits and credits, dates and decimal points in the US or European style — so Berm works out the shape of yours rather than asking you. There are steps for getting the file out of each bank, and the same steps are on the Import card in the app.

Import the same file twice and nothing changes. Import an overlapping range and only what is new is added.

Berm does not connect to your bank. There is no bank login and nothing is read from your account automatically: what Berm knows is the file you choose to give it. There is more on working without a bank login.

2. Confirm what repeats

Berm lists the bills and pay it found in your history. Tick the ones that are real, and the forecast changes as you tick.

Rent, pay, subscriptions, insurance, the gym: the things that decide the shape of a month are the things you stop noticing. Berm looks for anything landing on a schedule and suggests it, with the transactions it worked it out from.

Nothing is added until you confirm it. A projection is only as good as its rules, and a rule you did not agree to is a number you cannot check.

Your balance comes from the same export. Its running-balance column says what the account held after the last row, so there is nothing to type. An export without one leaves the balance to set on a slider instead — the one figure Berm cannot read for itself.

3. Read the projection

Berm walks forward a day at a time, applying your confirmed bills and an everyday spending rate read from your own history, and shows whether and when your balance goes under: the date, how long it stays under, how deep it gets, and which payments put it there.

What comes out is a closing balance for every day, anywhere from a month to a year ahead, not a monthly total — because a balance goes under on a day, and a month can add up and still have the rent land four days before the pay that covers it.

You set a cushion you want to keep above zero, and Berm will read the heaviest day your own bills produce and suggest a figure that clears it.

You also get the most you can spend on an average day between now and your next paycheck without going under, next to the pace you are actually on.

All of it is cards on one page, and what sits near the top is whatever your own figures put there — with the reason written on each card.

And while Berm is closed, it can tell you: an overdraft three days ahead, a bill the morning before it goes out, pay on the day, the week ahead on Mondays, or that your balance is getting old. Each kind is off until you switch it on, and there is never more than one a day.

If you plan with somebody, an import can tell them too. When a file finds something wrong — going under, an envelope over, a paycheck missing — the people who share that budget hear about it at once, and so does the person you keep a household with. You both switch it on. Good news goes the same way: a goal within reach or sooner, a card paid off, a payment back.

4. Choose a level of spending

If it goes under, Berm offers the most you can spend a day and never go under, and, if you keep a buffer, a lower figure that keeps that too. Or set your own figure on a slider and watch the forecast redraw as you move it. Choose one, and Berm tells you whether you are keeping to it.

The figure it offers holds across the whole forecast, not just until payday, because the rent that puts you under is usually the one after the next paycheck. When no amount of cutting back would be enough, it says so and names the payments in the way.

It is a forecast, not a guarantee. It assumes the weeks ahead look like your history, and it tells you the pace it is assuming.

What it does not do yet

Sooner from us than later from you.

• A notification is only as current as your last visit. Berm works out what to tell you while it is open, from the figures you have given it, so a week without an export is a week of notifications about last week's money. That is why one of the kinds is a reminder to export.
• On iPhone and iPad, notifications need Berm on the Home Screen. Apple sends them only to web apps added there, not to a Safari tab.
• A lost password cannot be recovered. Berm lets your password manager make it and checks the manager kept it, enrols a passkey while you set up, and tells you whenever there is only one way in. There is more on the privacy page.
• One account, and no bank holidays. There is no multi-account or transfer handling, and scheduled payments shift for weekends only.

To see it before you sign up, open the app: it opens on the sample, six months of a made-up history that goes under in a few weeks, with no account and nothing saved.