# How Much Cash Buffer Should a Small Business Keep?

Source: https://www.cashflowforecasttemplates.co.uk/guides/how-much-cash-buffer-should-a-small-business-keep
Updated: September 25, 2026

> Many small businesses aim to keep a cash buffer of four to eight weeks of fixed costs, such as payroll, rent and loan repayments. Businesses with seasonal or lumpy income, few large customers or long payment terms need more. The best way to set your buffer is from your cash flow forecast: cover the worst realistic shortfall plus a margin.

A cash buffer is the money you keep in the bank for when things don’t go to plan: a customer pays late, a van breaks down, a quiet month arrives earlier than expected. Too small and you’re one surprise away from missing payroll. Too large and money sits idle that could be growing the business. This guide explains the common rules of thumb and a better method based on your own forecast.

## Common rules of thumb

| Rule | Suits |
|---|---|
| 4 to 8 weeks of fixed costs | Most small businesses with steady income |
| 2 to 3 months of fixed costs | Seasonal businesses, or those with a few large customers |
| 3 to 6 months of operating costs | Cautious owners, businesses with volatile income |
| Enough to cover two payrolls | Very small businesses with weekly or fortnightly pay |

“Fixed costs” means the payments you must make even if sales stop: payroll and payroll taxes, rent, loan repayments, insurance and essential software.

## Calculate yours from your forecast

Rules of thumb are a starting point. A better buffer comes from your own numbers:

1. **List fixed costs per month.** For example: payroll $24,000, rent $4,000, loan $1,250, insurance and software $1,000. Total: $30,250.
2. **Look at your worst realistic month.** In your forecast or last year’s bank statements, find the biggest shortfall of cash in versus cash out in a single month. Say it was $14,000.
3. **Add your biggest single risk.** Your largest customer paying a month late might be $18,000.
4. **Set the buffer** to cover the larger of these risks plus a margin. Here, about $20,000 to $30,000, or roughly four weeks of fixed costs, would absorb either problem.

Then set it as the minimum balance in your forecast. Any month below it turns red.

## What pushes your buffer up

- **Seasonality.** The bigger your quiet season, the more you need to carry into it. See [seasonal businesses](/cash-flow-forecast-template/landscaping) for an example.
- **Customer concentration.** If one customer is 30 percent of sales, their late payment is your biggest risk.
- **Long payment terms.** The longer customers take to pay, the more cash you need to fund the gap.
- **High fixed costs.** Rent and salaries that can’t be reduced quickly need more cover.
- **No backup funding.** Without an agreed overdraft or credit line, cash is your only safety net.

## What lets you keep less

- Steady, recurring income, such as subscriptions or retainers
- Customers who pay immediately, like card sales
- Costs that fall when sales fall, such as commission or materials
- An agreed facility you can draw on quickly

## Examples by business type

**A café** with daily card takings and weekly food orders has fast-moving cash and costs that partly follow sales. Two to four weeks of fixed costs, plus a repair fund for equipment, is often enough, rising before a quiet season.

**A consultancy** with five staff and clients on 45-day terms has high fixed salaries and slow receipts. Six to eight weeks of payroll and rent is safer, more if one client is a large share of income.

**A construction contractor** with retainage held by clients and subcontractors to pay needs a larger buffer, often two to three months of fixed costs plus the cost of mobilising the next big job.

**An online shop** that buys stock months ahead should plan its buffer around the stock cycle: the lowest point is usually just before the peak season, when stock is paid for but not yet sold.

**A subscription business** with monthly card billing has steady income and can often run a smaller buffer, provided churn is stable and failed payments are retried.

## Buffer vs overdraft

An overdraft or credit line is useful backup, but banks can reduce or withdraw facilities, often exactly when the economy turns. Many owners keep a cash buffer for normal surprises and treat the facility as a second line of defence for genuine emergencies.

## Reviewing the buffer

Check your buffer at least twice a year, and whenever something big changes: a new hire, a new lease, losing or winning a large customer, or a change in payment terms. A buffer that was right when payroll was $15,000 a month is too small at $25,000. Your forecast makes the review quick: update fixed costs, look at the worst month in the coming year, and adjust the minimum balance setting.

## Building your buffer

If you don’t have one yet, build it steadily:

1. **Separate it.** Open a second account for the buffer.
2. **Set aside a percentage.** Move 3 to 5 percent of every receipt, or a fixed amount each month.
3. **Keep windfalls.** Put part of any unusually strong month straight into the buffer.
4. **Pause drawings or dividends** until the target is reached, if you can.
5. **Plan it in the forecast** so you can see when you’ll reach the target.

## Using the buffer

A buffer is for using, not admiring. When you dip into it, the forecast should show how and when it will be rebuilt. If you find yourself using it every month, the problem isn’t the buffer: it’s a structural gap between cash in and cash out that needs fixing. [Ways to improve cash flow](/guides/12-ways-to-improve-cash-flow-quickly) can help.

## Common mistakes

- **Counting money owed by customers as the buffer.** It isn’t cash until it arrives.
- **Keeping tax money as the buffer.** Sales tax and payroll tax you’ve collected belong to the tax authorities.
- **One number forever.** Review the buffer when your costs, customers or season change.
- **Too much.** Large idle balances in a growing business may be better used on stock, equipment or repaying expensive debt.
- **Mixing it with personal savings.** Keep the business buffer in the business, so it’s clear what the business itself can withstand.
- **No plan to rebuild it.** After using the buffer, schedule the top-up in the forecast straight away.

## Set a buffer in your template

Every template on this site has a minimum cash buffer setting. Any week or month below it turns red, and the summary counts how many periods fall short.


For a weekly view of how close you’ll get to your buffer, use the [13-week forecast](/guides/13-week-cash-flow-forecast).

### What is a cash buffer?
The minimum amount of cash a business aims to keep in the bank to absorb late payments, unexpected costs or a slow month without borrowing in a hurry.

### How many months of expenses should a small business keep?
A common rule is one to two months of fixed costs, or three to six months of operating expenses for more cautious owners. The right amount depends on how predictable your income is.

### Should an overdraft count as a buffer?
An agreed overdraft or credit line can be part of your safety net, but it can be reduced or withdrawn. Most owners keep some cash buffer as well.

### Where should I keep my cash buffer?
In an account you can access quickly, ideally separate from your day-to-day account so it isn’t spent by accident.

### How do I build a cash buffer?
Set aside a fixed percentage of receipts each month, keep part of any unusually strong month, and hold back owner drawings until the buffer is reached.