Your Basic authorization header was not encoded correctly.


  "code": "BasicAuthIncorrect",
  "target": "Unknown",
  "details": [
      "code": "BasicAuthIncorrect",
      "number": 35,
      "message": "Incorrect Base header format.",
      "description": "The Basic header must be in the format 'Basic (Base64Encoded(value))' where Value is either 'username' + ':' + 'password' or 'accountid' + ':' + 'licensekey'.  -0-",
      "faultCode": "Client",
      "helpLink": "",
      "severity": "Exception"


The published standard for HTTP authorization headers specifies that Basic authentication is performed by setting the “Authorization” header in the HTTP request to the following string:

Basic Base64(credential + ':' + secret)

An example header looks like this:

Basic AhD72dhkS8=

In the HTTP request you provided to AvaTax, your information was not correctly encoded. Common troubleshooting steps:

  • Did you forget to provide either a username or a password?
  • Did you remember to put a colon in between your username and your password?
  • Did you forget to Base64 encode the resulting string?
  • Did you accidentally Base64 encode the word "Basic"?
  • Are you using a library that automatically handles this encoding for you, and you accidentally encoded the value twice?

For more information on authentication, please read Authentication in REST v2.