Row context total of previous rows

Solved it myself ;), and want to share it, if in any case there is an easier way to do this, im still interested.

My calculated column formula is as follows:

'New column' =
CALCULATE ( SUM ( Table1[Amount] ); ALLEXCEPT ( Table1; Table1[Key] ) )
    - DATEDIFF (
        Table1[Date];
        CALCULATE ( MAX ( Table1[Date] ); ALLEXCEPT ( Table1; Table1[Key] ) );
        DAY
    )

Hi,

This M code (Query Editor) will also work

let
    Source = Excel.CurrentWorkbook(){[Name="Data"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Key", type text}, {"Date", type datetime}, {"Amount", Int64.Type}}),
    Partition = Table.Group(#"Changed Type", {"Key"}, {{"Partition", each Table.AddIndexColumn(_, "Index",1,1), type table}}),
    #"Expanded Partition" = Table.ExpandTableColumn(Partition, "Partition", {"Date", "Amount", "Index"}, {"Date", "Amount", "Index"})
in
    #"Expanded Partition"

Hope this helps.