The total tells you nothing. You need the line items.
Finance tells you you're over budget.
But the number itself doesn't explain anything.
You can't see:
The same overrun can come from very different things:
But the total looks the same.
If you want to understand *why*, you need to go deeper.
Break the Budget down. Is it one category - or several? Most overruns are concentrated in one place.
Look at the invoices behind the overrun. Now it starts to make sense: • who you bought from • what you bought • when
Look at what you expected. Is it: • the same items, just more expensive? • the same price, but higher volume? • something you didn't plan at all?
Once you see the line items, the cause becomes obvious. Most of the time it's: • price • volume • or something unplanned
When you can see the detail, the conversation changes.
From:
"We're over budget"
To:
"We're over budget because X increased by Y%"
You can:
A good answer is specific:
"We're 14% over on IT support because the contract increased in March. The price change wasn't reflected in the budget."
That shows:
Start from the invoices - not the total. Break the overspend down by category, then trace it to the specific purchases that caused it.
Because it’s aggregated. The total shows that something is wrong - not what caused it.
Typically one of three things: price changes, higher volume than expected, or unplanned purchases.
Go to line-level data. Compare what you actually bought with what you expected - supplier, price, and quantity.
Tie it to a specific change: "Costs increased because X changed" - not just "we’re over budget."
Trace every variance to the exact purchase