A personal profit and loss statement for your UK household, forecast forward

The P&L runs at two granularities: monthly and annual. Monthly is where you see the shape of a year, the months a big renewal lands in, and where a pay change bites. Annual is where you compare year against year across the whole forecast horizon. The annual view also carries a subtotal column, so you can total a line across the years you are looking at.

The row set is Income, Deductions from pay, Expenses and Net profit, with the below-the-line items sitting underneath. Every line drills down. Tap Income and you get each salary and each benefit award separately. Tap Deductions from pay and you get income tax, National Insurance, the pension contribution and any student loan repayment, which is the money taken before the pay ever reached you. Tap Expenses and you get housing, debt, utilities and living costs, each of which opens again into the individual items. Source and owner pills tell you where a figure came from and whose it is, and the whole statement goes landscape or fullscreen when the columns get wide.

The chart above it has three views rather than one, and they are not three time scales. Balance is the cumulative position, Movement is the profit or loss each period leaves behind, and Breakdown stacks the same year into where the income went before anything was left over. Both timeframes carry all three, so the question and the period are chosen separately.

This is the part that separates a household P&L from a tidied-up list of transactions, and it is worth being specific about what CrestCast actually does.

• Debt interest is split out from capital repayment. Only the interest is treated as a cost. The capital portion is you buying more of your own house, so it leaves the P&L and turns up in net worth instead.
• Depreciation is an expense above the line. An asset that loses value costs you money in the year it loses it, whether or not you sold anything.
• Unrealised revaluation sits below the line. If an asset is simply marked at a different value, that movement is reported separately and never inflates net profit.
• A realised gain appears when you genuinely sell something. Not before.
• Pension contributions are shown as their own item rather than being lost inside a take-home figure.
• A total return line brings the above-the-line and below-the-line halves back together, so you can see the operating result and the full picture without conflating them.

The discipline is the point. Net profit stays a clean measure of whether your household earns more than it costs to run, and the value movements that would blur it are kept where you can see them separately.

Almost every personal finance tool treats a car as a balance that quietly shrinks. CrestCast treats it the way an accountant would: a vehicle wears out, that wearing out is an operating cost, and it belongs above the line with your other expenses.

It is also not a flat guess. Vehicles depreciate on a year-of-manufacture ladder, because a two-year-old car and a twelve-year-old car do not lose value at the same rate. That is an unusual choice for a household tool, and it changes conclusions. A household that looks comfortably profitable on a cash view can be running at a much thinner margin once the car it replaces every few years is honestly costed.

You can enter salary, self-employment, rental and other income, and benefits. For salary you enter the gross and CrestCast works out UK income tax, National Insurance, workplace pension contributions and student loan repayments from it.

Multiple employments are handled properly, which sounds like a small thing until you have two jobs. Tax and student loan are aggregated across all of them against one set of thresholds and then apportioned back per job, rather than each employment being taxed as though it were the only one. Workplace pension contributions stay per employment, calculated on that job's own gross. Get that wrong and the take-home you plan around is wrong by hundreds a month.

Benefit is a first-class income type with a real DWP rate picker behind it, covering PIP, Attendance Allowance, Carer's Allowance, ESA and Universal Credit at 2026/27 rates. You choose the award and the component rather than hunting down the weekly figure and typing it in as a round number you will forget to update.

The pay recurrences match how these are actually paid, too: weekly, fortnightly, four-weekly and monthly. A four-weekly award is not a monthly one, and pretending otherwise gives you thirteen payments a year modelled as twelve. For a household where a carer's income, a disability award and a part-time salary all sit alongside each other, that detail is the difference between a forecast you can use and one you quietly stop trusting.

The statement has a perspective switch: your own, your partner's, the joint accounts on their own, or the two of you combined. Same statement, four honest answers, because “are we profitable” and “am I profitable” are different questions and couples need both.

How the joint side is divided comes from one household split figure, set once and applied throughout. It is a single global number, not a per-bill percentage, which keeps the arithmetic consistent and keeps the conversation about the split itself rather than about forty individual line items. More on the household picture on the page for couples.

Say the mortgage is £220,000 at 4.6% over 25 years. The payment is roughly £1,235 a month. On a cashflow view that is £1,235 out of the account and that is the whole story. On the P&L, only about £843 of that first payment is interest and therefore a cost. The other £392 is capital: it leaves your current account and arrives in your equity, so it belongs in net worth, not in expenses.

Now add the car. Say you paid £18,000 for it. No cash leaves your account this month because of it, but it is worth less at the end of the year than at the start, and CrestCast puts that fall in value into expenses on the year-of-manufacture ladder for its age.

You can build a household P&L in a spreadsheet. People do. The trouble is what it takes to keep it honest. You have to split every mortgage payment into interest and capital month by month as the ratio between the two shifts across the term, and redo it every time a rate changes or you overpay. You have to run a UK income tax and National Insurance calculation per job against shared thresholds, and reapportion it when either salary moves. You have to keep depreciation schedules for anything that wears out.

Each of those is a formula you have to get right once and then maintain forever. The failure mode is not that the spreadsheet breaks loudly. It is that a thresholds tab goes stale in April, or an amortisation column silently stops after row 300, and you carry on planning off a number that quietly stopped being true a year ago. See the three-way financial model explained for why the three statements only work when they are wired to each other.

Four edges that matter on this page, so you know exactly what the numbers rest on.

• Workplace pension contributions are all modelled as salary sacrifice, which gives National Insurance relief. If your scheme is relief at source or net pay instead, your modelled take-home comes out slightly optimistic.
• Self-employment is an income type, not self-assessment support. Class 4 National Insurance is charged on self-employed profit at its own rates and thresholds, but there are no payments on account and no allowable-expenses model: you enter profit after expenses.
• No Capital Gains Tax. When you sell something the gain shows as a memo line, and no tax is charged on it. If a sale is a big part of your plan, work the tax out separately.
• No bank connection. Nothing is pulled in automatically. You type your own numbers, or import a CSV you exported from your bank yourself, which is what makes this a forecast running years ahead rather than a report on last month.