VBA has native Date functions as well as a Date data type that allow for comparing and storing date information. The DateAdd function returns a future date (or previous date using a negative interval) using the specified interval. The interval can be in seconds, minutes, hours, days, months, weeks, or years. The DateDiff function will return the difference between two days in the specified interval.
The example below calculates a target date 180 days prior to the current date then finds all files in the specified folder that were last modified prior to the target date.
Sub Test() ArchiveFiles ActiveDesignFile.Path, 180 End Sub
Sub ArchiveFiles(strPath As String, numDays As Long) Dim dateTarget As Date Dim iDays As Long Dim strFile As String
' Target date is numDays before today dateTarget = DateAdd("d", numDays * -1, Date)
' find all files in current folder strFile = Dir(strPath & "\*")
Do While Len(strFile) > 0
' get the number of days since the file was created or last modified iDays = DateDiff("d", FileDateTime(strFile), dateTarget)
' If older than numDays send to archive
If iDays > numDays Then
' Archive file
strFile = Dir