This float value is the sales tax percentage rate applicable to the corresponding tax jurisdiction (US state or Canadian province). Sellers are responsible for providing accurate sales tax rates for each jurisdiction. This sales tax rate comes into play when a buyer from that tax jurisdiction makes a purchase from the seller. The value passed in is stored with a precision of 3 digits after the decimal point (##.###).
This field is only returned in order management calls if sales tax applies to the order line item, and is only in GetItem
(and other 'Get' calls) if sales tax is applicable to the listing or order line item, and the seller is the person making the call.
Although this field will be returned at the order level in order management calls for a single line item order, sales tax is applied at the line item level and not order level. For multiple line item orders, this field will not be returned at all at the order level. Note: As of September 1, 2020, buyers in over 40 US states will automatically be charged sales tax for eBay purchases. eBay will collect and remit this sales tax to the proper taxing authority on the buyer's behalf. So, if a sales tax rate is applied to the listing by the seller for a state that is subject to eBay 'Collect and Remit', the sales tax rate in this field is ignored by eBay during the checkout process. For a list of the US states that are currently subject to 'eBay Collect and Remit', see the eBay sales tax collection help topic.