Please be sure to include the 4-digit code after your zip code. This will help to ensure that the City receives its sales tax on retail sales and that it does not go to Oklahoma City. If you are not sure what 4-digit code you need to put after your zip code, you may contact the Post Office to obtain this information. You may also use their website at https://tools.usps.com/go/zip-code-lookup.htm, you will need to select the find by address option. Once you input the requested information, it will let you know what your 4-digit code is.