Filter dataset for previous month data

[Anonymous]

I see a few similar Dax queries to what I am trying to achieve but the only problem is I am not looking for a sum or total. I simple just want to filter the data set for last months data only. This is what I have so far but it is not working. Any ideas on how to get this to work?

DEFINE
VAR CostFilter = filter('Table01','Table01'[Date] >= date(year(now()),month(now()),1))

VAR Costcolumns = SUMMARIZECOLUMNS(
'Table01',
'Table01'[Tags - Copy.DepartmentNumber],
'Table01'[Tags - Copy.OwnerEmail],
'Table01'[Cost],
'Table01'[Date]

)
evaluate
Costcolumns

[tamerj1]

Hi @Anonymous 

Please try

DEFINE
VAR CostFilter = FILTER(VALUES(Table01'[Date]), 'Table01'[Date] >= EOMONTH ( TODAY ( ), - 1 )  + 1 )

VAR Costcolumns = SUMMARIZECOLUMNS(
'Table01',
'Table01'[Tags - Copy.DepartmentNumber],
'Table01'[Tags - Copy.OwnerEmail],
'Table01'[Cost],
'Table01'[Date],

TREATAS ( CostFilter, 'Table01'[Date] )

)
evaluate
Costcolumns