When One Customer Is Too Big a Share of Your Business

A landscaping company picks up a property management contract that's worth as much as ten regular customers combined. A boutique lands a wholesale order from a local hotel chain that becomes half its monthly sales. A contractor gets pulled onto one developer's projects almost full time. In the moment, this feels like exactly what you wanted — more revenue, less chasing new work, a calmer month.

The catch shows up later, usually the month that customer leaves.

Why a big customer is also a risk

There's nothing wrong with landing a large account. The risk isn't the size of the customer — it's what share of your total cash they represent. If one customer is 40% of your revenue and they pause, renegotiate, or walk away, you're not down 40% of a bad month. You're down 40% of every month until you replace them, and replacing that kind of volume rarely happens as fast as losing it.

It's also a quieter risk than it looks. A business with one dominant customer can have strong sales, healthy-looking margins, and a full schedule — right up until that one relationship changes, at which point all three numbers move at once.

How to tell if you're exposed

You don't need complicated analysis to check this. Pull your sales for the last three to six months and ask one question: what share came from your single biggest customer? As a rough guide:

• Under 15-20% is generally healthy — losing them would hurt, but wouldn't threaten the business.
• 20-35% is worth watching. Start treating that relationship as something to actively protect and diversify away from, not just enjoy.
• Above 35-40% means your business's health is largely tied to one relationship you don't fully control. That's the range where a single phone call could change everything.

It's easy to miss this if you're only looking at total sales. The number that matters here isn't "how much did we sell" — it's "how much of that came from how few people."

What to actually do about it

Don't turn down the big customer. The goal isn't to shrink your best account — it's to make sure it's not the only thing holding the business up.

1. Keep bringing in smaller, regular customers even when you're busy. It's tempting to stop marketing or quoting new work once one account fills your schedule. That's exactly when the gap grows, quietly, until the big account is the whole business instead of just the biggest part of it.
2. Watch payment terms on the big account separately. A large customer that pays net-60 while everyone else pays on the spot can create a cash flow gap even while business looks great — you're carrying their invoice for two months before it turns into cash you can use.
3. Build a reserve sized to that risk, not just your average month. If one customer disappearing would knock out a big share of revenue, your cash cushion should be able to cover more than a normal slow patch while you rebuild the customer base.
4. Have an honest conversation with yourself about the relationship. Is it under a contract, a handshake, a seasonal habit? Knowing how solid it actually is — and how much notice you'd realistically get if it ended — is more useful than assuming it'll simply continue.

Keep the picture visible, not just felt

The businesses that handle this well aren't the ones who avoid big customers — they're the ones who know, in plain numbers, how much of their cash flow rests on any single relationship, instead of just having a vague sense that "things are good right now." That way, if the big account does slow down or walk away, it's a planned-for dip in the numbers, not a surprise.

If you're using Clovemi to track your day-to-day sales and cash position, the optional Customers module lets you keep sales tied to individual customer records, so a question like "how much of our revenue is really coming from one account" is something you can actually check — not something you have to guess at.

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