UnspecifiedTimeZone
Example
{
	"code": "UnspecifiedTimeZone",
	"target": "Unknown",
	"details": [
		{
			"code": "UnspecifiedTimeZone",
			"number": 119,
			"message": "A timezone could not be determined from the datetime.",
			"description": "Please include a valid ISO 8601 time zone designator (e.g. 'Z' or '+00:00').",
			"faultCode": "Client",
			"helpLink": "http://developer.avalara.com/avatax/errors/UnspecifiedTimeZone",
			"severity": "Error"
		}
	]
}
Explanation

This indicates that you specified a date/time value without a timezone. Please indicate the specified timezone for the date/time field.