How to read your P&L without an accounting degree

If you've ever opened your monthly Profit & Loss statement and felt your eyes glaze over by line three, you're in good company. Most founders we meet were never trained to read one — and most accountants weren't trained to explain one in plain English.

The good news: a P&L only has five lines that really matter on a day-to-day basis. Get fluent in those, and you can run the business without needing to memorise UK GAAP.

The five lines that matter

1. Revenue (a.k.a. sales, turnover, top-line)

This is the money your customers paid you — or owe you — in the period. Note: not the cash that hit the bank. UK accounting is "accrual" by default, which means revenue is recognised when you earn it, not when you bank it.

Question to ask: if revenue moved up or down materially this month, what changed? New customers? Price change? A one-off invoice that wasn't really recurring?

2. Cost of sales (a.k.a. cost of goods sold, COGS)

The direct costs of delivering whatever your customers bought. For a SaaS company, that's hosting, third-party APIs and customer success time. For e-commerce, it's the product, packaging and shipping. For an agency, it's the salaries of the people who did the work.

Question to ask: is this growing in step with revenue, or faster? If COGS is outpacing revenue, your unit economics are eroding.

3. Gross profit (and gross margin)

Revenue minus COGS. The slice you have left to run the rest of the business. As a percentage of revenue, this is your gross margin — and it's the single most important number on the P&L for most startups.

If you take one thing from this article: know your gross margin. Most SaaS businesses target 75–85%. Most agencies, 40–60%. Most physical product, 30–50%. If you're miles outside the band for your sector, something needs investigating.

4. Operating expenses (a.k.a. overheads, OpEx)

Everything that isn't a direct cost of delivery. Salaries (the indirect ones), rent, software subscriptions, marketing spend, professional fees. Usually broken into categories like Sales & Marketing, R&D and General & Administrative.

Question to ask: are these growing in line with the plan? Founders frequently underestimate how SaaS subscriptions creep up — it's worth a quarterly tidy.

5. Operating profit (and the bottom line)

Gross profit minus operating expenses. This is what your business actually made (or lost) before tax. Below this you'll see interest, depreciation and tax — important, but usually not where the levers are.

What to look for when reading a monthly P&L

A good monthly review takes about 15 minutes. We suggest this order:

1. Look at the trend, not the month. A single month can be noisy. Always view at least 3 months side by side.
2. Compare to budget. If you have one, the variance column is where the insight lives.
3. Find the biggest mover. What line changed most vs last month? Does it have an explanation?
4. Check gross margin. Is it stable? Improving? Eroding? Why?
5. Cash burn rate. Operating loss divided by 30 = roughly your daily burn. Multiply by months of cash on hand = your runway.

The mistakes we see founders make

• Confusing cash and P&L. You can be profitable on paper and out of cash. Always read the P&L next to your cashflow.
• Coding everything to "Sundry expenses". If 30% of your costs are in a catch-all bucket, your P&L can't tell you anything useful. Coding takes 30 seconds; getting it right matters.
• Reviewing the wrong period. Late-month invoices and timing differences can make month-on-month comparisons noisy. Quarter-on-quarter is usually a more reliable read.
• Ignoring deferred revenue. If you take annual subscriptions upfront, the cash hits your bank in month 1 but the revenue is spread over 12. Many founders book it all as revenue immediately — and then panic about why month 2's "revenue" is so low.

What good looks like

If you're reading your P&L on the 10th of each month, with commentary from your accounting team, and you can explain the two biggest movers without having to phone anyone — congratulations, you've got management information. That's a different position than "having an accountant".

And if you can't? That's the gap City Solution closes. Our Growth and Scale packages include a monthly management pack with commentary, plus a quarterly review with your accounting manager to walk through the trends.

Next up: our companion article on SEIS & EIS explained for founders — because once you understand your P&L, the next question is usually how to fund the next leg of growth.