MustAssignUserToCompany
Example
{
	"code": "MustAssignUserToCompany",
	"target": "Unknown",
	"details": [
		{
			"code": "MustAssignUserToCompany",
			"number": 63,
			"message": "Company users must be assigned to a company.",
			"description": "The user -0- is of security role -1-, which must be assigned to company.  Please set the companyId value to the ID of a company.",
			"faultCode": "Client",
			"helpLink": "http://developer.avalara.com/avatax/errors/MustAssignUserToCompany",
			"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.

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. You will receive this error if you create a Company level user with a companyId value of zero or null, or with a companyId number that does not exist in this account.