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.
1 If you are on the ZIP code field, only numerical values can be entered. If you try to enter a letter in the ZIP code field, it will not be entered as a value. ZIP code should be entered as a 5-digit number.  Phone numbers must be entered with three-digit area code, three digit prefix, and 4-digit number.