Budget vs actual (budget versus actual, or variance reporting) sets the plan for a period next to the outcome and shows the difference — as an amount and as a percentage — by revenue line, cost head, department, site or project. Actuals come from the accounting system or ERP; the budget usually lives in a spreadsheet, because that is where it was built. Year-to-date variance and the full-year forecast ("actuals so far plus budget for the rest") are the two views most boards ask for.
The report matters because it is how a business notices drift early. A department that is 4% over budget in month two is a conversation; the same department found 15% over at year end is a write-off. It also matters because variance is where arguments start: was the budget wrong, or the spending? A report that shows both at the line level, with the ability to drill to the transactions behind a variance, settles those arguments faster than one that shows totals.
The practical difficulty is joining two sources with different shapes: budgets are monthly by account and department; actuals are transactions by date and ledger. A reporting tool has to relate them on account, period and department, and handle accounts that exist in one and not the other.
In Klayara the budget sheet is connected as a table (Google Sheets or Excel), related to the ledger from your accounting system on account, period and cost centre, and the variance, year-to-date and forecast measures are formulas written once and reused across every dashboard. See formulas and calculations and the finance snapshot template.