Creating a flag for previous month

the code I posted can only replace 4 in your example, try this:

#"Added Conditional Column" = Table.AddColumn(#"Sorted Rows", "Provider is new last month", each if [Provider start date] > #date(Date.Year(Date.StartOfMonth(DateTime.FixedLocalNow())-#duration(1,0,0,0)), Date.Month(Date.StartOfMonth(DateTime.FixedLocalNow())-#duration(1,0,0,0)), 1) then 1 else 0),

Hi Anonymous,

there are build-in date functions which you can use: Date.IsInPreviousMonth and Date.IsInCurrentMonth.

let
    DateToTest = #date(2019, 5, 5),
    Result = {
         Date.IsInPreviousMonth(DateToTest),
         Date.IsInCurrentMonth(DateToTest)
    }
in
    Result

Usage in your case:

#"Added Conditional Column" = Table.AddColumn(#"Sorted Rows", "Provider is new last month", each if Date.IsInPreviousMonth([Provider start date]) or Date.IsInCurrentMonth([Provider start date]) then 1 else 0),

or even shorter if you expect just a logical type (True/False as result):

#"Added Conditional Column" = Table.AddColumn(#"Sorted Rows", "Provider is new last month", each Date.IsInPreviousMonth([Provider start date]) or Date.IsInCurrentMonth([Provider start date]), type logical),