How to Do Variance Analysis on Your Cash Flow Forecast

A forecast is a set of predictions; variance analysis is how you find out which predictions were wrong and why. It’s the step most small businesses skip, and the one that makes the biggest difference to forecast accuracy. Done weekly or monthly, it takes fifteen minutes and turns every surprise into a better assumption for next time.

What variance analysis is

For each line of the forecast and each finished period:

Variance = actual − forecast

Then express it as a percentage of the forecast, and explain the reason for anything material.

For cash in, a negative variance is bad (less arrived). For cash out, a positive variance is bad (more left). Colour-coding helps: our templates show unfavourable variances in red and favourable ones in green.

Deciding what’s material

Don’t explain every dollar. A common rule is to investigate any variance over 10 percent of the line, or over a fixed amount (for example $1,000), whichever is larger. In the example, receipts, suppliers and energy need a note; card sales don’t.

Timing or permanent?

This is the most useful question in variance analysis:

• Timing variance: the money moved in a different period than forecast, but will still move. Late customer payments, a supplier paid early, a tax payment moved to next week. Move the amount to the period it will now happen.
• Permanent variance: the money won’t arrive, or will cost more. A lost order, a price increase, a bad debt. Adjust this period and every future period affected.

In the example, the $5,500 of receipts is timing (the clients paid in the next month), while the supplier price rise is permanent and should be built into every future month.

The variance routine

1. Enter actuals for the finished period from your bank statement or accounts.
2. Calculate variances for every line (a template does this automatically).
3. Flag material variances above your threshold.
4. Explain each one in a few words.
5. Classify as timing or permanent.
6. Adjust the forecast: move timing differences to their new period, and apply permanent ones to all future periods.
7. Look for patterns across several periods.

Patterns worth watching

• Receipts consistently below forecast: customers pay slower than you assume. Change your payment timing assumptions, and see how to forecast receivables.
• Costs consistently above forecast: prices have risen, or small costs are missing from the forecast.
• Big variances in the same line every month: that line needs a better method, not just a new number.
• Favourable variances that reverse next month: usually timing, such as a bill paid late.

Cumulative variance

Look at variances year to date as well as for the latest period. A $500 shortfall each month is minor on its own and $6,000 over a year. The cumulative view also shows whether timing differences are genuinely catching up or quietly becoming permanent.

Worked example across three months

Three months in, the business is $13,300 behind forecast. Most of it came from customer receipts landing later than forecast. The owner changes the collections assumption from 30 to 45 days across the whole forecast, and the lowest balance later in the year moves $9,000 lower, below the buffer. Without variance analysis, that would have been a surprise in June.

Variance in a 13-week forecast

In a weekly forecast, variances are smaller and more frequent, and most of them are timing. The key is to follow each one: if a $6,000 payment expected in week 3 arrives in week 5, the week-3 variance is −6,000 and the week-5 variance is +6,000. Keep a short running list of timing items not yet resolved, so you can see at a glance which late receipts are still outstanding and chase them. If an item is still on the list after four weeks, reconsider whether it’s really timing.

A quick checklist

• Actuals entered for every line, from the bank statement
• Variances calculated and material ones highlighted
• Each material variance explained in a few words
• Each classified as timing or permanent
• Timing items moved to their new period
• Permanent changes applied to all future periods
• Cumulative variance checked for drift
• The lowest balance ahead reviewed after the changes

Reporting variances

If you report to a partner, lender or board, a one-page summary is enough: net cash flow forecast vs actual, the three largest variances with reasons, whether each is timing or permanent, and what’s changed in the forecast as a result. Lenders value forecasts that show honest variances with clear explanations more than forecasts that always look perfect.

Who should see the variances

Share a short variance summary with whoever owns each line: the person managing sales should see the receipts variances, and whoever buys from suppliers should see the supplier variances. They usually know the reason immediately, and they’re the ones who can make the next forecast better. Keeping variances within the finance function alone wastes most of their value.

Common mistakes

• Only looking at the bottom line. Net variance can hide large offsetting differences.
• Explaining without adjusting. The point is to improve the forecast, not just record what happened.
• Treating timing as savings. A bill paid late isn’t money saved.
• Changing the forecast after the fact to make variances disappear. Keep the original forecast for comparison.
• Setting the threshold too low. Explaining every small difference takes time and hides the ones that matter.

Templates with variance built in

Premium templates include an Actuals tab and a Variance tab that calculate every line automatically, colour-coded, with year-to-date totals and percentages for total cash in and cash out. Enter what happened and the analysis is done for you. See the templates by industry, and read about improving forecast accuracy.