If you have a Single select Time filter with Year/Semister/Quarter/Month then use the below expression to get the Time in Months.
in <<>> brakets put UniqueName
IIF(<
>.Level.Ordinal=4,(<>.Parent.Parent.Parent,<>.Parent.Parent.Parent.PrevMember),
IIF(<>.Level.Ordinal=3,(<>.Parent.Parent,<>.Parent.Parent.PrevMember),
IIF(<>.Level.Ordinal=2,(<>.Parent,<>.Parent.PrevMember), (<>,<>.PrevMember)
)
)
)
If you need current year and previous year.
IIF(<>.Level.Ordinal=4,(<>.Parent.Parent.Parent,<>.Parent.Parent.Parent.PrevMember),
IIF(<>.Level.Ordinal=3,(<>.Parent.Parent,<>.Parent.Parent.PrevMember),
IIF(<>.Level.Ordinal=2,(<>.Parent,<>.Parent.PrevMember), (<>,<>.PrevMember)
)
)
),
IIF(<>.Level.Ordinal=4,(<>.Parent.Parent.Parent,<>.Parent.Parent.Parent.PrevMember),
IIF(<>.Level.Ordinal=3,(<>.Parent.Parent,<>.Parent.Parent.PrevMember),
IIF(<>.Level.Ordinal=2,(<>.Parent,<>.Parent.PrevMember), (<>,<>.PrevMember)
)
)
).PrevMember