What a Profit and Loss Forecast Actually Does

A profit and loss forecast is a simple table that shows what you expect to earn, what you expect to spend, and what should be left over. It usually covers twelve months, split into monthly columns, with a total at the end. Unlike a cash flow forecast, which tracks the timing of money moving in and out of your bank account, a profit and loss forecast answers a different question: is this business actually making money?

That makes it useful in several practical situations. You might need one to support a loan or mortgage application, to work out whether a new contract is worth taking, or simply to see whether your pricing covers your costs. For sole traders and limited companies alike, the process is the same. The detail differs, and we will come to that.

Start with Your Sales Figures

Income is the hardest part to forecast honestly, because it is the number you want to be high. Start with evidence rather than ambition.

• Break income into streams. If you sell products and also do consultancy, forecast them separately so you can see which one is pulling its weight.
• Use what you already know. Last year's invoices, signed contracts, recurring retainer clients and a realistic view of your pipeline are all better starting points than a guess.
• Allow for seasonality. A landscaper, a wedding photographer and a retailer all have quiet months. Spreading income evenly across twelve months flatters the quiet periods and hides problems.
• Do not forecast your best month as your average. If your strongest month was £8,000 and your weakest was £3,000, your average is not £8,000.

If you are not sure, forecast low. A forecast that assumes modest growth and beats expectations is far more useful than one that assumes a boom and never delivers.

Build Your Cost List in Two Parts

Split your costs into fixed and variable. Fixed costs stay roughly the same whatever you sell: insurance, accountancy fees, software subscriptions, rent, phone and broadband, professional memberships. Variable costs rise and fall with your work: materials, stock, subcontractors, courier charges, payment processing fees, travel.

Then add the costs people forget. These are the ones that turn an optimistic forecast into a misleading one:

• Tax and National Insurance. A sole trader pays Income Tax and Class 4 National Insurance on profits, plus payments on account. A limited company pays Corporation Tax on its profits, and if you take a salary, employer's National Insurance is a business cost.
• Pension contributions, whether personal or through a workplace scheme.
• Replacing equipment. A laptop, van or set of tools wears out. Spreading that cost across the year is more honest than ignoring it until it fails.
• Bad debts and late payment. A small percentage written off each year is realistic for most businesses.
• Your own drawings or salary. Sole traders should show drawings separately from business costs, but they still need to come out of the profit.

If you are VAT registered, use net figures throughout and leave VAT out of the forecast entirely. It is not your money.

Do the Arithmetic and Sense-Check It

Subtract total costs from total income for each month. What remains is your forecast profit. Now check whether the result is believable. If your forecast shows a 60 per cent profit margin and similar businesses in your sector run at 15 to 20 per cent, something in your figures is wrong.

Look at the shape of the year, not just the annual total. A year that ends profitable but has four consecutive loss-making months in the middle will still put pressure on your bank balance. That is a cash flow problem, but your profit and loss forecast will reveal it first.

Review It Monthly, Not Once a Year

A forecast written in January and filed away is decoration. Put a recurring date in your diary, ideally the same week each month, and do three things:

• Compare your actual income and costs against the forecast for that month.
• Ask why any line is more than about ten per cent out, and write down the reason.
• Update the remaining months based on what you now know.

Keeping a rolling twelve-month view means your forecast always looks a year ahead rather than shrinking towards December. When you win a new contract, raise your prices, take on an employee or lose a major client, adjust the forecast the same week. It takes ten minutes and keeps the document trustworthy.

Keeping the Numbers Honest

The most common mistake is optimism in both directions: rounding income up and costs down. The second is treating a forecast as a target to be defended rather than a tool to be corrected. Neither helps you.

A simple profit and loss forecast does not need software or complicated formulas. A spreadsheet with twelve columns and a list of income and cost lines will do. What matters is that the figures come from something real, that you review them regularly, and that you change them when your business changes. Do that, and you will spot a difficult quarter while there is still time to do something about it.