Every figure in the platform covers a span of time. Which span is selected changes the number.
The common ranges
Month to date — from the first of the current month until today. Early in a month this is a few days, not a month, and it will always look small against a completed month.
Year to date — from the start of the financial year until today.
Last complete month — the previous month in full. The only one of the three that is comparable with another month without adjustment.
Why this is the first check on a surprising figure
Two numbers covering different windows differ by exactly the amount you would expect. It accounts for more apparent discrepancies than every other cause combined — see a number looks wrong.
Which date is used
A transaction is placed by the date it cleared rather than the date it was initiated. A card payment made on the last day of a month and settled two days later belongs to the following month.
This is normal and it is why month boundaries never divide activity exactly.
Comparing
Against the same period a year earlier holds seasonality constant, which is the comparison that carries meaning in a trade whose demand follows the weather.
Against the previous month is only meaningful where the business is not seasonal, and even then the number of working days differs between months.
Partial periods
A range ending today includes an incomplete day and, in most trades, incomplete records for the last few days. Figures near the edge of a range firm up as records arrive — see how often data updates.
The financial year
Not necessarily the calendar year. Year to date runs from the start of the business's own financial year — see accounting periods.