How to create a business budget —
a practical guide for small companies

A personal budget and a business budget share the same basic logic — know what's coming in, know what's going out, and plan ahead rather than reacting. But a business budget carries extra layers a personal one doesn't: tax sitting as a future liability rather than an immediate deduction, revenue that can be genuinely unpredictable month to month, and decisions about reinvestment versus drawing profit out. This is a practical, step-by-step approach built for sole traders and small limited companies.

Step 1 — forecast revenue conservatively

Start with your realistic, not optimistic, revenue. If you have trading history, use your actual monthly figures from the last 12 months as your baseline, adjusted for any known changes ahead (a client ending a contract, a new recurring client starting, a seasonal pattern). If you're newer and don't have 12 months of data, build a bottom-up estimate from your pipeline and sales capacity rather than a top-down guess at "market share."

The single most common budgeting mistake in small businesses is building a budget around hoped-for revenue rather than demonstrated revenue, then discovering months later that cost commitments were made against income that never materialised.

Step 2 — separate fixed costs from variable costs

• Fixed costs — rent, software subscriptions, insurance, salaries, loan repayments, accountancy fees. These continue whether or not you make a sale this month.
• Variable costs — cost of goods sold, contractor or freelancer costs tied to specific work, commission, shipping, transaction fees. These should move roughly in line with revenue.
• Semi-variable costs — utilities, some marketing spend, travel. Worth tracking separately since they sit between the two and are easy to lose track of.

Knowing your fixed cost base specifically matters because it tells you your break-even point — the minimum revenue you need each month before the business is profitable at all. Many business owners can't state this number precisely, which makes it very difficult to judge whether a quiet month is a problem or just normal variation.

Step 3 — budget for tax as it's earned, not when it's due

A simple fix: as part of your monthly budget, set aside a fixed percentage of profit into a separate tax reserve account the moment it's earned, so the money is already there when the liability falls due, rather than needing to be found from that month's trading.

Tax	When it's actually earned	When it's typically due
Corporation Tax	As profit is made through the accounting year	9 months and 1 day after the company's year end
VAT	On each sale, if VAT registered	Usually quarterly, 1 month and 7 days after the quarter end
Income Tax on dividends/salary	As drawn through the tax year	Via Self Assessment, by 31 January following the tax year

Step 4 — build in cash flow headroom, not just profitability

A business can be profitable on paper and still run out of cash — this happens constantly, particularly where customers pay on long payment terms, stock needs to be bought ahead of sale, or a large one-off cost lands in a quiet revenue month. A budget needs to model cash timing, not just total profit and loss for the year.

1. Map out when money actually lands, not when an invoice is raised — if customers typically pay 30 or 60 days after an invoice, your budget needs to reflect that lag.
2. Hold a cash buffer — a common starting point for a small business is one to three months of fixed costs held in reserve, more if your revenue is seasonal or concentrated in a small number of clients.
3. Time large purchases deliberately, rather than letting them fall wherever is convenient — avoid committing to a large piece of spend in a month where a tax payment or a quiet revenue period also lands.

Step 5 — decide a reinvestment versus drawings split, deliberately

For limited company directors in particular, how much profit to leave in the company to reinvest versus how much to draw out as salary and dividends is a genuine budgeting decision, not an afterthought. A sensible approach is to set this as a rule rather than deciding ad hoc each month — for example, committing to a fixed drawings amount each month (see our guide to building a personal budget on irregular income for how to convert that into stable personal cash flow) while leaving a defined portion of profit in the business for growth, tax reserves, and a cash buffer.

A simple monthly business budget structure

Category	What it covers
Revenue	Realistic forecast based on trading history or confirmed pipeline
Fixed costs	Rent, subscriptions, salaries, insurance, loan repayments
Variable costs	Cost of goods sold, contractor costs, commission, transaction fees
Tax reserve	Set-aside percentage for Corporation Tax, VAT, and payroll taxes as they're earned
Cash buffer contribution	Ongoing top-up toward a 1–3 month fixed-cost reserve
Reinvestment	Equipment, marketing, hiring, stock — planned growth spend
Owner drawings	Salary and dividends, ideally a stable monthly figure rather than ad hoc

Review monthly, not annually

An annual budget set once in January and left untouched tends to drift badly out of date by the summer. A short monthly review — actual revenue and costs against budget, tax reserve balance checked against the liability actually accruing — keeps the budget a living tool rather than a document nobody looks at again until next year's version is due.

This article is for general information purposes only and does not constitute financial advice. Individual circumstances vary — consider speaking to a qualified adviser for personalised guidance.