Time inteligense in Perfromance Point Server

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