"code": "TaxpayerNumberRequired",
	"target": "Unknown",
	"details": [
			"code": "TaxpayerNumberRequired",
			"number": 9,
			"message": "taxpayerIdNumber is required for customers subscribing to Avalara Returns.",
			"description": "Customers who have an active MRS or CSP service must provide their United States taxpayerIdNumber (TIN) for all company records.",
			"faultCode": "Client",
			"helpLink": "",
			"severity": "Error"

Customers who subscribe to Avalara Managed Returns or Certified Service Provider services must identify all companies by their US Taxpayer ID Numbers (TIN). In general, a taxpayer ID number is either an Employer Identification Number (EIN) assigned by the Internal Revenue Service or a Social Security Number (SSN) assigned by the Social Security Administration.

EIN numbers are in the format 12-3456789, whereas most SSN numbers are in the format 123-45-6789. The number is used to correctly report taxes on your returns and to correctly match your corporate entities with your tax returns.