How to build a cash reserve for your business

Why a reserve matters

A cash reserve is money set aside specifically to absorb the unexpected — a big customer paying late, a quiet quarter, a sudden cost, a downturn. It's the difference between a setback you ride out and one that forces panic borrowing or worse.

It's closely tied to your runway: a reserve is, in effect, runway you've deliberately banked. Profit and turnover don't protect you in a bad month — liquidity does. A business with a buffer makes decisions from a position of strength; one living hand-to-mouth is one late invoice from trouble.

Work out how big it should be

The common rule of thumb is three to six months of essential operating costs — but the right figure depends on your business:

• Size it against fixed and unavoidable costs (payroll, rent, core overheads), not total spend you could cut.
• Volatile or seasonal income argues for a larger buffer.
• Long debtor days or customer concentration argue for more, since a single late payer hurts more.
• Steady, diverse, recurring revenue can justify a smaller one.

A quick way to pressure-test your target: how long could the business cover the essentials with the doors open but no money coming in? That number is what you're insuring against.

Build it from trading

A reserve is built deliberately, a bit at a time, not found in one lump:

1. Treat reserve-building as a fixed monthly transfer, like any other bill — pay it first, not from what's left.
2. Move it to a separate account so it isn't spent by accident in the day-to-day.
3. Direct windfalls — a strong month, a tax rebate, a one-off — straight into it.
4. Free up cash to feed it by cutting debtor days and tightening your working capital cycle.

Consistency matters more than size: a modest, automatic monthly transfer compounds into a real buffer within a year, where waiting for spare cash that never quite appears builds nothing.

Where a standby facility fits

Cash reserves and a credit facility solve the same problem — surviving a shock — from two angles, and the strongest position uses both. A reserve is your own money, instantly available, costing nothing to hold but tying up cash that can't work elsewhere. A standby facility is borrowing capacity you arrange in advance and draw only if needed.

A flexible working-capital facility agreed before you need it acts as a second line of defence: if a shock outlasts your reserve, you draw on the facility rather than scrambling to raise finance under pressure — and arranging it calmly beats borrowing in a crisis. Many businesses hold a working reserve and a standby line, so a long or large shock doesn't exhaust both at once.

Keep it disciplined

A reserve only works if it's protected and maintained. Set a clear policy for what counts as a genuine emergency — a real cash crisis, not a tempting opportunity or a slow month you could manage — so the buffer isn't quietly eroded.

If you do draw on it, make rebuilding it the priority once trading recovers, just as you'd repay a facility. Review the target as the business grows: a reserve that covered three months two years ago may now cover three weeks. Treated with discipline, the reserve becomes a permanent source of resilience rather than a pot that's always almost empty.