let
Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Birthdate", type date}, {"ActionDate", type date}}),
#"Added Custom" = Table.AddColumn(#"Changed Type", "Age", each Date.Year([ActionDate]) - Date.Year([Birthdate]) -
(if Date.Month([ActionDate]) < Date.Month([Birthdate]) then 1 else
if Date.Month([ActionDate]) = Date.Month([Birthdate]) and Date.Day([ActionDate]) < Date.Day([Birthdate]) then 1 else 0))
in
#"Added Custom"
#"Added Custom" = Table.AddColumn(#"Changed Type", "Age", each
if [Birthdate] = null
then
null
else
Date.Year([Appl Dt]) - Date.Year([Birthdate]) - Number.From(Date.ToText([Birthdate], "MMdd") > Date.ToText([Appl Dt], "MMdd")))