Profit and Loss Statement Explained: How to Read Your P&L

The profit and loss statement, usually shortened to P&L, answers the question every business owner asks: are we making money? It shows your income and expenses over a period, a month, a quarter or a year, and what's left at the end. This guide explains each part of a P&L, how to read it and which numbers deserve your attention.

What a P&L looks like

A simple P&L for a small service business for one month:

The parts of a profit and loss statement

Income (revenue)

What you earned from sales in the period. Under accrual accounting, that's what you invoiced, whether or not you've been paid yet. VAT you charge isn't income: it belongs to the tax authority, so it sits in a liability account, not here.

Cost of sales

Costs directly tied to delivering what you sold: materials, stock, freelancers on client work, payment processing fees. If you sold nothing, these costs would mostly disappear.

Gross profit and gross margin

Income minus cost of sales. Gross margin is gross profit as a percentage of income. In the example, £9,000 ÷ £12,000 = 75%. Gross margin tells you how much each pound of sales contributes towards your overheads.

Operating expenses

The costs of running the business whatever you sell: rent, software, insurance, marketing, salaries and professional fees.

Net profit

What's left after every expense. If it's negative, it's a net loss, and a good P&L says so plainly rather than showing a "net profit" of minus £800.

How to read your P&L like an owner

1. Start with the bottom line, then work upwards to understand why.
2. Compare periods. This month against last month, and against the same month last year.
3. Watch gross margin. Falling margin with steady sales usually means delivery costs are creeping up or prices haven't kept pace.
4. Look at expenses as a share of income, not just in pounds. Marketing rising from 5% to 12% of income is a decision worth checking.
5. Separate one-offs. A large one-off expense can make a good month look bad.

Profit isn't cash

The P&L can say you made £3,250 while your bank balance went down. Common reasons:

• Customers haven't paid their invoices yet (check your aging report)
• You bought equipment, which appears on the balance sheet, not as an expense all at once
• You repaid a loan, which reduces a liability rather than counting as an expense
• You paid VAT to the tax authority

That's why you need both the P&L and the balance sheet, and why the choice between cash and accrual accounting changes what your P&L shows.

Where the P&L comes from

In double-entry bookkeeping, the P&L is built from your income and expense accounts. Every invoice, bill and expense you post lands in one of them. Get the bookkeeping right and the P&L builds itself; see double-entry bookkeeping explained for how.

A P&L that's always up to date

Zelvorm Books builds your profit and loss statement straight from your journal, so it's current the moment you post an invoice or a bill. It labels a loss as a net loss, and it's free for small businesses.

Four P&L ratios worth tracking

In the example above, gross margin is 75%, net margin is about 27% (£3,250 ÷ £12,000), and expenses are about 48% of income. Track these monthly and the trend tells you more than any single month.

Monthly vs annual: reading different periods

• Monthly P&Ls show trends and catch problems early, but they're noisy. One big invoice can make a month look great.
• Quarterly P&Ls smooth out the noise and are useful for planning.
• Annual P&Ls are what your accounts and tax return are based on.
• Year-to-date compares where you are against the same point last year.

For seasonal businesses, always compare a month with the same month last year rather than the month before.

Using your P&L to set prices

Your P&L tells you what each sale needs to cover. If your monthly operating expenses are £5,750 and your gross margin is 75%, you need about £7,700 of sales a month just to break even (£5,750 ÷ 0.75). Every pound above that, at the same margin, adds 75p of profit.

If break-even feels too close to your normal sales, you have three levers: raise prices, reduce direct costs (raising gross margin), or reduce overheads. The P&L shows which one has the most room.

Service vs product businesses

• Service businesses often have small cost of sales (mainly freelancers or subcontractors) and high gross margins, with most costs in wages and overheads.
• Product businesses have significant cost of sales (stock, shipping, packaging), lower gross margins, and need to watch stock levels on the balance sheet too.
• Hybrid businesses should split income and cost of sales by line, for example 4100 Product sales and 4110 Services, to see which part makes money.

Common P&L mistakes

1. Including VAT in income, which overstates sales.
2. Counting equipment purchases as expenses; they belong on the balance sheet and are depreciated.
3. Owner drawings as expenses in a sole trader's books; they're not a business cost.
4. Loan repayments as expenses; only the interest is an expense.
5. Missing accruals, so a month looks cheaper than it was because a bill arrived late.

What to do with your P&L each month

1. Read the bottom line and compare it with last month and last year.
2. Check gross margin and the biggest expense lines.
3. Note anything unusual and find the transaction behind it.
4. Look at your bank balance and aging report alongside it.
5. Decide one action: chase a payment, review a cost, adjust a price.

Ten minutes a month is enough to stay in control.

The short version

A P&L shows income minus expenses over a period. Read it from the bottom up, track gross margin, compare periods, and remember that profit and cash are different things.