Private Sub CommandButton1_Click()
Dim month_a, month_b, month_c, j As Integer
Dim currentm, defaultm As Long
Dim pvt As PivotTable
Dim coll As Collection
Dim PivotRefs, i As Variant
Application.ScreenUpdating = False
On Error Resume Next
'Identify all PivotTables within active worksheet and transform into an array
Set coll = New Collection
For Each pvt In ActiveSheet.PivotTables
coll.Add pvt.Name
Next
ReDim PivotRefs(0 To coll.Count - 1)
For j = 1 To coll.Count
PivotRefs(j - 1) = coll.Item(j)
Next
'Start collecting data on what you wish to filter
currentm = Application.InputBox(prompt:="I'd like to check whether you're a robot. How many months have this project been running since January 2014?", Type:=1)
month_a = Application.InputBox(prompt:="Enter the first month you'd like to filter by", Type:=1)
month_b = Application.InputBox(prompt:="Enter the second month you'd like to filter by (Click 'cancel' if none)", Type:=1)
month_c = Application.InputBox(prompt:="Enter the third month you'd like to filter by (Click 'cancel' if none)", Type:=1)
defaultm = 1
'Uncheck every filter
For i = 0 To coll.Count - 1
For defaultm = 1 To currentm
ActiveSheet.PivotTables(PivotRefs(i)).PivotFields("MONTH").PivotItems(defaultm).Visible = False
Next defaultm
Next i
'Debugging Area
For i = 0 To coll.Count - 1
Debug.Print PivotRefs(i)
Next i
Debug.Print coll.Count
'Check required filter
For i = 0 To coll.Count - 1
With ActiveSheet.PivotTables(PivotRefs(i)).PivotFields("MONTH")
.PivotItems(month_a).Visible = True
.PivotItems(month_b).Visible = True
.PivotItems(month_c).Visible = True
End With
Next i
End Sub