A cashflow forecasting app for UK households

Most tools give you one time scale and expect you to live with it. The cashflow here has three, and they answer genuinely different questions.

• Daily covers a quarter at a time, and you step from quarter to quarter. This is where you find the trough between the mortgage going out on the 1st and payday on the 28th.
• Monthly covers one forecast year at a time. This is the working view for the next twelve months, and it is where most decisions get made.
• Annual runs the whole way out to the ten-year horizon, one bar a year. Every forecast projects ten years ahead, so this is the long view of the same numbers rather than a second model. Ten years is a deliberate choice rather than a limit, and here is why it is not thirty.

There is no weekly view and no quarterly view. Weekly, fortnightly, four-weekly and quarterly exist as recurrences you can put on a bill or an income, so money lands on the right dates, but they are not separate ways of reading the forecast. You can see the same view in miniature as the cashflow view on the CrestCast overview.

Cash asks two questions and one pill switches between them. Balance is a stock: what is actually there at each period end. Movement is a flow: what came in and what went out over the period. Both carry all three period lenses, so you can ask either question day by day, month by month or year by year. The same two pills sit on profit and loss and on net worth, so the control does not change meaning when you change tab.

A second row underneath decides how far into that answer the chart goes. Summary plots the quantity itself: the running closing balance under Balance, the period's surplus or deficit under Movement. Breakdown groups it, with cash in stacked above the line and cash out below it, in bands that match the statement rows printed underneath. Detail goes one level further and names every account and pot on its own series, so you can see which one is doing the growing instead of reading a single combined line.

Not every pair has a chart behind it, and only the pairs that do are offered. There is no per-account view of cash movements, because a pound that moves between two people's accounts cannot be attributed to one of them without guessing, and a guessed figure is worse than none.

Breakdown carries the balance across it as a line on its own right-hand axis, because a six-figure balance plotted against a few thousand pounds of monthly flow would flatten every bar to a pixel otherwise. Where you hold savings as well as a current account, a second dashed line splits the two, so you can see whether it is the pot or the spending account doing the growing.

Inc savings decides whether the pots are folded into the running balance at all, and High-low adds the highest and lowest point reached inside each period to the balance chart, which is how you catch a month that ends fine having dipped hard in the middle. Real terms restates every figure in today's money, which matters most on the annual view: a balance ten years out is worth reading as what it would buy, not as what it would say on a statement.

A chart on its own is a shape. The statement is where the shape becomes accountable. Under every view sits a table with one column per period, and it does not move when you change the chart. It always reads the same way: the opening balance, everything that moved, and the closing balance those movements arrive at. Cash in, deductions from pay, cash out and transfers are the movement rows, and the lowest and highest point reached inside the period sit with the balances. Opening plus movement equals closing, in every column, so you can check the arithmetic rather than trust it.

Every parent row opens up. Tap cash in or cash out and you get the line items behind them: this salary, that mortgage repayment, the council tax, the car insurance. Tap deductions from pay and you get income tax, National Insurance and the pension contribution separately, which is money that never reached the current account and so is shown apart from the cash rather than inside it. Opening and closing balance open too, into the accounts that make them up. Each row carries pills telling you where the money went and whose it is, which is the bit that matters in a household where not everything is joint. There is a landscape and fullscreen mode for when you want the whole grid rather than a phone column.

Cashflow is also the only one of the three statements carrying a subtotal column on all three views. Profit and loss has one on the annual view only, and net worth has none, because stocks do not sum.

Take a joint account with the mortgage leaving on the 1st, council tax on the 5th, the smaller direct debits through the first fortnight, and the contributions that fund it all landing on the 28th. On the monthly view that household looks fine: money in covers money out, closing balance steady. Nothing to see.

Switch to daily for the quarter and a different picture shows up. In the month the £480 annual car insurance premium falls due on the 16th, everything lands before any money arrives, and the account spends nearly two weeks overdrawn that the monthly average never mentions.

A forecast built entirely from estimates drifts. So you can pin the real figure: tap a cell in the cashflow statement for one item in one month and record what genuinely went in or out. Eight kinds of item can be pinned: an income, a bill, a joint contribution, a transfer, a planned one-off, a salary, a member's income and a savings contribution. An explicit £0 is a real pin, meaning nothing moved that month, which is different from having no pin at all. A manage list holds every pin you have made.

The pin is not a note. It feeds the engine, so the balance for that month and everything downstream of it re-reckons from the real number rather than the estimate.

Two things to know before you go looking. First, pinning is done by tapping a cell on the daily cashflow view, and only there. It is not available on the monthly or annual cashflow view, and not on the profit and loss or net worth statements. The app opens on monthly, so you have to switch to daily to find it. Second, this is not budget versus actual. There is no budget in CrestCast and no variance figure anywhere. Pinning replaces the estimate with what happened. It does not report the gap between them, and it will never tell you that you overspent by £73 on groceries.

Do you have to type everything in? Not all of it. The Bills screen and the Incomes screen both offer a CSV import. Export a statement from your bank, feed it in, and CrestCast looks for the same payee appearing at least twice on a regular schedule and turns those into recurring forecast items: bills, incomes and joint bills.

It is a deliberately narrow tool, and the narrowness is what keeps your data yours:

• It reads one fixed format. The header must be exactly date,description,amount.
• Dates must be DD/MM/YYYY. A negative amount means money out.
• No OFX, no QIF, no bank-specific templates, no column mapping screen.
• It does not store your transactions, and it does not pin actuals. It creates forecast items and stops.

And it is emphatically not a bank connection. Nothing is pulled from your bank, ever. You export a file yourself and you choose what goes in.

Plenty of people run a cashflow in a spreadsheet, and for one person with four bills it is fine. The trouble starts when it has to survive contact with real life.

You hand-roll a row per bill and encode the recurrence yourself, so quarterly water and four-weekly something-else each need their own formula. Then a pay date shifts by three days and every date-anchored row downstream needs re-anchoring. Then the mortgage fixed rate ends and the payment changes partway through, so you split the row in two or quietly leave it wrong. Then you want ten years out instead of two, and you rebuild the whole grid, because in a spreadsheet the columns are the horizon.

The real problem is not the effort. It is that a broken spreadsheet keeps working. It carries on producing a confident number long after the number stopped being true, and there is nothing in it that can tell you. A cashflow you cannot trust is worse than no cashflow, because you act on it.

CrestCast does not connect to your bank. No Open Banking, no account aggregation, no automatic transaction sync. Everything the forecast knows, you told it. If what you want is a live feed of yesterday's card spending, several other apps do that well and this is not one of them. What you get for that is a forecast built from your plans rather than your past, with no credential shared and nothing read from your accounts.

It is also not budgeting software. It forecasts forward rather than classifying backwards, so there are no spending categories to police and no variance report. If you want the difference between the two disciplines set out properly, we wrote it up in cashflow versus profit and loss.

Cashflow is one of three statements built from the same set of facts. Profit and loss tells you whether the household is actually making money once interest and depreciation are accounted for. Net worth tells you what you are worth as it changes. Cashflow tells you whether the money is in the account on the day it is needed, which is the one that stops you at the till.

They agree with each other by construction, because they are three readings of one engine rather than three models. Change a bill and all three move. Schedule a pay rise for next April and all three move from April. A spreadsheet almost never manages that, because there the three tabs are three separate acts of bookkeeping.