TODAY() & NOW(): Calculated Column vs Measure Timing

TODAY() and NOW() return the current date (or date and time) — but when "current" actually gets evaluated depends entirely on whether the function is used in a calculated column or a measure.

TODAY()
NOW()

Calculated Columns: Frozen at Refresh Time

DaysSinceOrder = TODAY() - [OrderDate]

A calculated column is computed once, during data refresh, and the result is physically stored in the model — same as any other column. TODAY() inside it gets evaluated exactly once, at that refresh, and the stored result doesn't change again until the next refresh actually runs.

Five days after a refresh with no new refresh run, a DaysSinceOrder calculated column still reports the day count as of the refresh — not the actual current day count. The column isn't wrong, exactly; it's just showing a value that was correct when it was computed, not a live one.

Measures: Re-Evaluated Every Time the Report Is Viewed

Days Since Order := TODAY() - MIN(Sales[OrderDate])

A measure isn't stored — it's calculated at query time, every time a visual renders or a user interacts with the report. TODAY() inside a measure reflects the actual current date at that exact moment, regardless of when the underlying data was last refreshed.

Data last refreshed: September 1
5 days pass, no new refresh runs
Calculated column "DaysSinceOrder": still based on September 1        (frozen)
Measure "[Days Since Order]":       based on today's actual date      (live)

Common Mistakes

Expecting a Calculated Column With TODAY() to Update Daily

It only updates on the next data refresh — a scheduled refresh running once a week means a TODAY()-based calculated column is only ever as fresh as that week's most recent refresh, not the literal current day.

Using a Calculated Column When a Measure Was Needed

If the actual goal is "always reflect today's real date, live, whenever the report is opened," that's a measure's job — a calculated column using TODAY() can't do this regardless of how often it's refreshed, since it only recalculates on refresh, not on view.

Assuming NOW()'s Time Component Behaves the Same Way

The same refresh-time-vs-query-time split applies to NOW() — a calculated column using NOW() freezes not just the date but the exact time of the last refresh, which can look like a strange, arbitrary timestamp far removed from whenever someone actually looks at the report.

Not Considering Which Machine's Clock TODAY()/NOW() Reflects

Beyond when it's evaluated, TODAY()/NOW() also reflect whichever machine actually runs the refresh or the query — see DateTime.LocalNow() and the Desktop-vs-Service Trap for the same underlying issue on the Power Query side.

Best Practices

• Use a measure, not a calculated column, whenever a value genuinely needs to reflect the literal current date every time the report is viewed.
• If a TODAY()-based calculated column is required (for query-folding or performance reasons in a very large model, for instance), treat its value as "as of the last refresh," and refresh often enough that staleness doesn't matter for the use case.
• Document which refresh schedule a TODAY()-based calculated column depends on, since its apparent "bugginess" is usually just an unrefreshed model, not a formula error.

Next Steps

• Measures
• Calculated Columns
• DateTime.LocalNow() and the Desktop-vs-Service Trap
• DAX Function Reference