In the global settings, can you check to see if you have the Shipping is taxable checkbox checked?

Yes @Rusty, it is checked. And it calculates ok afterwards when invoicing and the payment. Now i have calculated the shipping quote and saved it to the invoice and is showing taxes ok. I dont know if i have done it correctly, i have to pass the shipping costs selected to get the quote (i think would be better passing the value instead of the rate) this is my code:

public ActionResult GetImpuestos(decimal gastosEnvio, string paisCOD="ES")
        {


            var shipAd = new Address()
            {
                AddressType = AddressType.Shipping,
                CountryCode = paisCOD
            };

            var shipment = this.Basket.PackageBasket(shipAd).FirstOrDefault();
            var shipmentRateQuotes = shipment.ShipmentRateQuotes().ToArray();
            var quote = shipmentRateQuotes.FirstOrDefault(s => s.Rate == gastosEnvio);


            var checkoutManager = this.Basket.GetCheckoutManager();

            if(quote!=null)
              checkoutManager.Shipping.SaveShipmentRateQuote(quote);

            var invoice = checkoutManager.Payment.PrepareInvoice();


            var taxationContext = MerchelloContext.Current.Gateways.Taxation;
            var tax = taxationContext.CalculateTaxesForInvoice(invoice, shipAd);
            decimal impuestos = tax.TaxAmount;

            return Json(impuestos);
        }

Take into account that in sale preparation you have to clear shipment rate quotes before saving it again.

Is there a way to set a fixed tax rate to a region inside a country?

Thanks Rusty, i will check it. As an improving idea for future versions, could this regions be outside of merchello.config to allow clean updates? like a regions_ES.config, so we could share it?

@Rusty my site is on production now and have a problem with a customer calculating taxes this way. It gets a null invoice. I have checked IsReadyToInvoice() and its false so it makes sense. What may be the issue here? how could i troubleshoot this? I have tried adding this settings to the checkout manager:

var settings = new CheckoutContextSettings()
            {
                ResetCustomerManagerDataOnVersionChange = false,
                RaiseCustomerEvents = false,
                EmptyBasketOnPaymentSuccess = true
            };

i'm thinking is something with this customer basket, other baskets works ok.

Yes @Rusty i am passing the settings each time. But note that at the point of this error is before confirming the sale. I only do it to calculate taxes to show on the checkout process. So it is the first time in the process i generate the invoice. Although it gets null, if i confirm the order it goes ok, so i think it is something to this "GetImpuestos" method:

  public ActionResult GetImpuestos(string shippingMethodKey, string paisCOD="ES", string region="", decimal gastosEnvio = 0)
            {
                decimal impuestos = 0;

                var settings = new CheckoutContextSettings()
                {
                    ResetCustomerManagerDataOnVersionChange = false,
                    RaiseCustomerEvents = false,
                    EmptyBasketOnPaymentSuccess = true
                };
                var checkoutManager = this.Basket.GetCheckoutManager(settings);

                if (string.IsNullOrEmpty(paisCOD))
                    paisCOD = "ES";

               //this is a default address only to calculate taxes for this country/region
                var shipAd = new Address()
                {
                    AddressType = AddressType.Shipping,
                    CountryCode = paisCOD,
                    Region = region
                };

                var shipment = this.Basket.PackageBasket(shipAd).FirstOrDefault();
                var shipmentRateQuotes = shipment.ShipmentRateQuotes().ToArray();
                var quote = shipmentRateQuotes.FirstOrDefault(s => s.ShipMethod.Key.ToString() == shippingMethodKey);




                if (quote != null)
                {
                    checkoutManager.Shipping.ClearShipmentRateQuotes();
                    checkoutManager.Shipping.SaveShipmentRateQuote(quote);
                }

//This is where i get false and i dont know why...

                if (checkoutManager.Payment.IsReadyToInvoice())
                {


                    var invoice = checkoutManager.Payment.PrepareInvoice();


                    var taxationContext = MerchelloContext.Current.Gateways.Taxation;
                    var tax = taxationContext.CalculateTaxesForInvoice(invoice, shipAd);
                    impuestos = tax.TaxAmount;
                }
                else
                {
//Temporal workaround, as i know for spain is 0.21
                    decimal amount = gastosEnvio + this.Basket.TotalBasketPrice;
                    impuestos = decimal.Round(amount * (decimal)0.21, 2);
                } 

                return Json(impuestos);
            }

Thanks Rusty, now it works, i have added this lines:

checkoutManager.Customer.SaveShipToAddress(shipAd);
checkoutManager.Customer.SaveBillToAddress(shipAd);

I thought that using the PackageBasket would be enought to know the taxes, but it makes sense to use BillingAdress.

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