CannotAssignUserToCompany
Example
{
	"code": "CannotAssignUserToCompany",
	"target": "Unknown",
		"details": [
		{
			"code": "CannotAssignUserToCompany",
			"number": 62,
			"message": "Security role cannot be assigned to a company.",
			"description": "The user -0- cannot be assigned to company -1-, because that user has security role -2-.  Only CompanyAdmin and CompanyUser level users can be joined to a company.",
			"faultCode": "Client",
			"helpLink": "http://developer.avalara.com/avatax/errors/CannotAssignUserToCompany",
			"severity": "Error"
		}
	]
}
Explanation

In AvaTax, a user may be either part of the overall account, or the user may be joined to a specific company within the account.

If you are an Account-level user, the companyId value on your UserModel will be null or zero. Attempting to assign an account-level user to a company will result in this error message.

If you are a Company-level user, the companyId value on your UserModel will be set to the ID number of the company to which you are assigned.