You can put all these entries in a single table with a field added that stores "single" for the left hand column and "Married" for the right hand column.
Then your relationship to this table can include a pair of Marital Status fields as part of the relationship:
Employee::Wage < withholding::NotOver AND
Employee::MaritalStatus = Withholding::MaritalStatus
(sort withholding records in this relationship in descending order by NotOver.)