Fill Down Group Headers in Power Query M

Fills blank cells in a group-header column with the value above them, common in exports where a header only appears once per group.

Data CleaningBeginnerfill downgroup headersblankcleaning

Power Query M code

let
    Source = YourTable,
    FilledDown = Table.FillDown(Source, {"GroupColumn"})
in
    FilledDown

Notes

Make sure blank cells are actual nulls, not empty strings, before running Table.FillDown - use the Replace Blank Strings with Null snippet first if needed.

Requirements

A table with a column where group values are only entered once and left blank for following rows.

How to use this snippet

In Power BI Desktop, choose Transform data to open Power Query, then open the Advanced Editor on a query (or start from a blank query).
Paste the snippet and replace the placeholder names (tables, columns, file paths) with your own. Check the requirements above first.
Run it through the Power Query M Formatter to tidy the layout.

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