Entity Model Name :
TestLinqDataContext db = new TestLinqDataContext();
var innerQuery = (from fb in db. TagMasters orderby fb.ExpirationDate descending select fb.ExpirationDate).Take(3).Distinct();
var result = (from f in db.TagMasters
where innerQuery.Contains(f.ExpirationDate)
// Notice here, grouping by a constant value
group f by 1 into g
select g.Max(t => t.ExpirationDate) );