How to build a budget for your SME - updated September 2026

Why is it so important to take the time to set a budget for your SME? 

I advocate budgeting because it provides a clear financial plan for where you want your business to go, while making the assumptions behind that plan visible. It’s not about predicting the future with perfect accuracy. Instead, it’s about making sensible assumptions, understanding the financial impact of your decisions, and having the insight to know when you need to act. 

For an SME, a good budget can help you: 

• Put the financial context behind your business goals and objectives, including the risks and opportunities you face. 

• Understand where you are spending money and how those costs may change over the coming year.

• Identify opportunities to improve margins or reduce unnecessary costs. 

• Plan for different scenarios, such as stronger-than-expected sales, losing a major customer or facing higher supplier costs. 

• Work out whether you can afford investments such as new premises, equipment or additional staff. 

• Support discussions with lenders or investors if you are looking for funding. 

• Give your team clear targets and help everyone understand what needs to happen for the business to achieve its goals. 

For SMEs, that might mean a manufacturer planning new machinery, a retailer managing stock and seasonal demand, or a professional services business deciding when it can afford to recruit. The details vary by sector, but the budgeting principles are similar. 

How to build a budget 

1. Bring together stakeholders 

Firstly, I suggest getting everyone with a stake in the numbers around the same table. In a larger business, that might be sales, operations, production and finance. In a smaller one, it may be just a few people, or even you alone, in which case the task is to look at the budget from each of those angles in turn. 

Budgets can become battlegrounds if people are working from different assumptions, and even a one-person view can be internally inconsistent (for example, planning ambitious sales without allowing for the time or cash needed to deliver them). So it's important to agree on the business's goals and objectives before getting into the detail of the numbers. 

If everyone agrees on the principles, the next steps should be much easier. If you're the sole decision-maker, ask yourself how the plan looks to your customers, your suppliers, your team, and your bank. 

I also find it useful to make the assumptions explicit. For example, if the plan assumes 10% sales growth, where exactly will that growth come from? Existing customers, new customers, higher prices, new products, or additional capacity? And do you have the people, stock, and cash to deliver it? 

2. Estimate sales 

To estimate future sales, start with what you already know. 

Your financial history should tell you what has sold, to whom, when, and through which sales channel. Look at trends, seasonality, customer concentration, and the sales level you can realistically deliver. 

The person responsible for sales should agree to the budgeted sales levels for existing customers as well as any realistically achievable new business. 

Timing matters too. Consider planned promotions, seasonal demand, customer ordering patterns, and any large contracts. A January sale or Black Friday promotion may increase sales but can also affect margins and cash flow. 

If you are a newer business without much historical information, use what you do know: the size of your market, your target customers, your sales pipeline and relevant competitor or industry information. Then sense-check your assumptions. 

One of the most common budgeting mistakes I see is forecasting increased sales without considering what is required to deliver them. More sales may mean more stock, materials, staff, advertising, premises, or working capital. 

3. Estimate cost of sales 

Once you know what you are expecting to sell, work with the operations or production team to estimate the costs required to deliver those sales. 

Cost of sales is mostly variable, meaning it changes with the amount you sell. For a manufacturing business, this might include materials, production labour, packaging and delivery. For a service business, staff time is often the highest direct cost. 

Use your purchase ledger and recent supplier invoices rather than relying on old prices. 

This is particularly important when costs have been moving around. UK inflation is now much lower than the peak seen in recent years, but it has not disappeared: CPI inflation was 3.1% in August 2026, while average regular pay growth was around 3.5% in the latest ONS figures. 

I would therefore avoid applying one blanket inflation percentage to everything, since materials, subcontractors, wages, transport and utilities may all behave differently. 

For more information, see my article on Costings, which explains how to understand the true cost of producing your products. 

4. Estimate overheads 

Overheads are the costs of running the business that do not necessarily move directly with sales. Examples include rent, insurance, software, professional fees, utilities and administration costs. 

Start with your historical profit and loss and check current supplier contracts and commitments, then look ahead. Are you taking on additional premises? Is an energy contract due for renewal? Are you planning to recruit? Have insurance, software subscriptions or professional fees changed? 

Salary and associated costs deserve particular attention. Budgets should include detailed person-by-person calculations based on actual wages and expected pay rises, and should also include National Insurance, pension and any benefit costs. From April 2026, employer National Insurance is 15% above the £5,000 secondary threshold for the 2026/27 tax year, and the National Living Wage for workers aged 21 and over is £12.71 an hour from 1 April 2026. 

5. Profit 

Using your sales, cost of sales and overhead assumptions, you can now build your profit and loss budget. 

Does the expected level of sales generate the gross margin you need? Is there enough profit to support your plans? If not, you can test the available levers: pricing, sales volumes, product mix, staffing, supplier costs or overheads. 

I normally find it much more useful to have this conversation before the year starts, rather than discover six months in that the original plan was never achievable. 

It is also worth running a few scenarios. What happens if sales are 10% below plan? What if a key material increases by 10%? What if you need to recruit two months earlier than expected? You do not need a complicated financial model - a handful of realistic scenarios can tell you a great deal. 

6. Capital expenditure 

Identify any major investments or capital expenditure you plan to make during the budget period, such as machinery, vehicles, IT equipment or premises improvements. These purchases can have a significant impact on cash, even though the accounting treatment is different. 

Capital expenditure does not hit the profit and loss account in full when you buy the asset. Instead, the cost is recognised through depreciation over its useful life, and is subject to relevant accounting and tax treatment. 

For budgeting purposes, I therefore look at it from all sides: what the investment does to reported profit, how the balance sheet/ fixed asset values alter, and when the actual cash needs to leave the bank account. This is particularly important for growing manufacturers and other asset-heavy businesses with substantial cash requirements. 

7. Cash 

The profit and loss budget is essential, but it is not the full picture - you also need to understand how cash will move in and out of the business. 

Profitable businesses can run into serious difficulties if they run out of cash, and growth can make this worse because you may have to pay for stock, materials and wages before your customers pay you. 

Your cash budget should therefore take account of the actual timing of receipts and payments. For example, if staff are paid at the end of each month, their wages become a cash outflow immediately. If customers have 30-day payment terms, the related sales may not turn into cash until the following month at the earliest. 

You should also include VAT, PAYE, Corporation Tax, loan repayments, capital expenditure and other significant cash commitments. 

For more advice, see my article on Cash Flow. 

Budgeting in 2026: the tools have moved on 

The basic budgeting principles have not changed, but the tools available to SMEs certainly have. 

Cloud accounting software can now provide much more up-to-date information without relying on spreadsheets being manually updated. Dashboards can bring sales, margins, cash and other key measures together, while forecasting tools can make it easier to model different scenarios. 

AI-assisted forecasting is also becoming more common. I see it as a useful support rather than a replacement for financial judgement. Technology can identify trends, automate some of the work, and help you test scenarios, but someone still needs to decide whether the assumptions make commercial sense. 

For me, the best approach is usually a combination of reliable bookkeeping, sensible technology and experienced financial judgement. Technology is only as good as the information going into it! 

Reviewing your budget 

A budget should not be created, filed away and forgotten. 

Each month, your management information should include a comparison of actual results against budget. This helps you understand where the business is performing differently from plan and, importantly, why. 

For more information, see my article on What Is Management Information and Eight Reasons You Need It for Your SME. 

I normally recommend reviewing the budget in stages: 

• After Q1: Compare actual performance with the budget and update any assumptions that have clearly changed. This is normally a light-touch review. 

• Halfway through the year: Carry out a more detailed review using the additional information you now have. Six-plus months on, things will have changed, and they should be incorporated into this update. 

• After Q3: Prepare an updated full-year outlook. This helps with any financial planning required before year-end, e.g., pension contribution payments, and can become the starting point for next year's budget, which should be a relook across all areas of the business. 

You do not necessarily need to rebuild the whole budget every time. If the original process was robust, the first review should often be a relatively light touch. The important thing is to keep the budget relevant and use it to support decisions. 

What if there are disagreements about the budget? 

Budget discussions can sometimes expose different priorities within a business. An owner may want 10% growth, while the sales team may not believe there is enough pipeline to achieve it. An operations manager may want additional staff, while the finance team is concerned about the effect on margins and cash. 

That is not necessarily a bad thing. A good budgeting process should bring these differences into the open so that the management team can discuss them and agree on what is realistic. 

Final thoughts 

There is little point in creating a budget if the financial information underneath it is inaccurate. As I discussed in From Bookkeeping to Boardroom, a strong finance function is built from the foundations upwards. Good bookkeeping and financial controls provide reliable data; reliable data enables meaningful management information; and that management information gives you the confidence to budget, forecast, and make better strategic decisions. 

 Your budget should include assumptions around Interest rates and inflation. As I write this in September 2026, the Bank Rate stands at 3.75%, wage growth is 3.5%, and inflation is at 3.1% (August 26); these rates or other assumptions should be built into your budget. 

The purpose of a budget, therefore, is not to predict the future perfectly. It is to turn your plans and assumptions into a financial framework that you can use to make decisions. By understanding what is driving your numbers, you can see the potential financial consequences of your choices, monitor what actually happens against your expectations, and identify when something is changing that may require you to act. 

That is where budgeting becomes much more than an annual finance exercise. Done well, it becomes part of a wider finance function that helps you understand where your business is today, where you want it to go, and what you may need to do to get there. 

If you would like to talk through your budget, cash flow, or wider financial planning, I am always happy to have an informal conversation. Sometimes a fresh pair of eyes is all that is needed to turn a collection of numbers into a useful tool for making better decisions.