One Basket, All Your Eggs: A Sober Look at Single-Client Dependence

There is a particular kind of arithmetic that few sole traders carry out, and it is the most revealing sum in the whole of your business: what percentage of last year's income came from a single source?

For many freelancers and sole traders we advise, the answer is uncomfortably high. Sixty, seventy, occasionally ninety per cent of turnover from one client. It feels secure — the work is steady, the relationship is warm, the invoices are paid. But dependence of that magnitude means your business is, in substance, an employee with none of the protections. One restructuring, one procurement review, one change of personnel, and the income you have built your life around can be gone by the end of the quarter.

The Risk Is Financial, Not Just Emotional

The obvious concern is psychological — the anxiety of putting all your eggs in one basket. But at Pomfrey Accountants, the more pressing issue is what concentration does to your finances.

Consider cash flow first. A single dominant client usually means a single dominant payment cycle. If that client moves to 60-day terms, or a payment is disputed, your entire household or business budget is exposed at once. There is no second income stream to smooth the dip. Reserves that look adequate on paper can be consumed quickly when there is no diversity behind them.

Then there is the tax dimension, which is where concentration quietly complicates things.

What Concentration Means for Your Tax Planning

Cash basis decisions. If you trade on the cash basis, your taxable income tracks money actually received. With one client, a delayed payment doesn't just strain your bank balance — it can defer tax into a later year, creating a lumpier liability profile. Diversified income tends to smooth this out, making your Self Assessment bill more predictable.

VAT strategy. If you are hovering near the £90,000 registration threshold, a single large contract can push you over it abruptly. Voluntary registration is one thing — we have written before about the deliberate case for it — but registration forced by one contract, with no room to absorb the VAT cost, is quite another. Diversification gives you options: you can plan the timing, assess flat-rate suitability, or structure growth deliberately rather than reactively.

Payment on account. If your tax bill exceeds £1,000, HMRC will ask for payments on account — twice-yearly instalments. When most of your income arrives from one source, timing those payments against one client's payment schedule is precarious. Two or three income streams give you more than one tap to draw from.

Testing Your Exposure

We suggest clients run a simple annual stress test. Ask yourself:

• If your largest client disappeared tomorrow, how many months could you cover your commitments from reserves?
• How long, realistically, would it take to replace that income — and what would you charge in the meantime?
• Do you know what proportion of your turnover sits with each client, to the nearest five per cent?

If the answers make you wince, you are not alone. But wincing is not a plan.

Practical Steps Toward Diversification

You do not need to transform your business overnight. Small, deliberate moves compound:

1. Set a concentration ceiling. Decide, in advance, that no client should exceed a set share of turnover — 40 per cent is a common benchmark — and treat breaching it as a signal to market for new work.
2. Convert project work into retainers. A retainer with a smaller client provides steadier cash flow than a large, sporadic contract, and smooths the gaps between bigger engagements.
3. Ring-fence the surplus. While you are concentrated, deliberately save a larger proportion of that client's income — it is your insurance premium against their departure.
4. Review annually with your accountant. Concentration creeps up gradually. A yearly conversation about your income mix keeps it visible.

A Final Word

Diversification is not a betrayal of a good client relationship. It is what allows you to serve that client well without fear, and to negotiate from a position of strength rather than desperation. Dependable businesses, like dependable advice, are built on more than one foundation.

If you would like to talk through how your income structure affects your tax position — or stress-test your numbers before the next Self Assessment deadline — we are always happy to sit down and go through them. Clear numbers, after all, are what we are here for.