I don't know your table occurrence names so replace my names with yours:
Globals::gStartdate < PortalTO::Date AND
Globals::gEndDate > PortalTo::Date
This type of range filtering can also be implemented at the relationship level instead of as a portal filter. There is also a way to use a return separated list of dates instead of inequalities--which may update your portal more quickly if implemented at the relationship level.
To get the starting date for a year to date date range:
Set Field [Globals::gStartDate ; Date ( 1 ; 1 ; Year ( get ( CurrentDate ) ) ]