The problem with investigating everything
A mid-sized business might have two hundred line items on the P&L. Every month, nearly all of them will show some variance from budget. If the finance team investigates every deviation, they will spend their entire reporting cycle writing variance commentary that nobody reads.
The solution is a structured threshold framework that separates signal from noise.
Setting your thresholds
Effective variance thresholds use two dimensions simultaneously:
Absolute threshold. The variance must exceed a minimum pound amount. For a business with £10 million in annual revenue, a threshold of £5,000 to £10,000 per line item is common. Variances below this are immaterial regardless of the percentage.
Percentage threshold. The variance must exceed a minimum percentage of budget. A common range is 5% to 10%. A £50,000 line item that is off by £2,000 (4%) is within normal operating variation.
Both must be exceeded. A £500 line item that is 200% over budget (£1,500 actual vs £500 budget) crosses the percentage threshold but not the absolute threshold. It is noise. A £2 million line item that is 1% over budget (£20,000 variance) crosses the absolute threshold but not the percentage. It is probably noise too. Focus on variances that cross both.
Differentiate by account type
Not all accounts warrant the same thresholds. Revenue variances deserve tighter scrutiny than expense variances because they cascade through the entire P&L. Consider:
- Revenue: 3% and £10,000
- Cost of goods: 5% and £5,000
- Headcount costs: 5% and £10,000
- Discretionary expenses: 10% and £5,000
Favourable vs unfavourable
Favourable variances (under-spend, over-performance on revenue) deserve investigation too. An expense line that is consistently 20% under budget might indicate delayed projects, unfilled positions, or sandbagged budgets. An investigation might reveal a timing issue that will reverse next quarter -- important context for forecasting.
The investigation workflow
When a variance crosses the threshold, the investigation should answer three questions:
1. What caused it? Was it a volume change, a price change, a timing shift, or a one-off item?
2. Is it permanent or temporary? Timing variances (an invoice that arrived a month early) reverse naturally. Permanent variances (a lost customer) affect the forecast.
3. What action is needed? Some variances require intervention (reallocating budget, adjusting the forecast). Others simply need explanation (a known seasonal pattern).
Automating threshold monitoring
Manually scanning the P&L for threshold breaches each month is tedious and error-prone. An FP&A platform can flag threshold breaches automatically, highlight the relevant line items, and route them to the appropriate budget owner for commentary. The finance team reviews the flagged items rather than the entire report.