One of the advantages for employees in a group health plan is the contribution most employers make toward the cost of the health coverage premium â in many cases, employers pay one-half or more of the monthly premium for an employee.
The basic format consists of five decimal numerical digits. An extended ZIP+4 code, introduced in 1983, includes the five digits of the ZIP code, a hyphen, and four additional digits that determine a more specific location within a given ZIP code. The USPS provides a free online lookup tool for ZIP codes.
The +4 on the ZIP Code is often the last four digits of the box number, zero plus the last three digits of the box number, or, if the box number is less than 4 digits, zeros followed by the box number. Since there is this variance, the ZIP+4 Code must be looked up individually for each Post Office Box.