Tax Lines in Cart Module
In this document, you’ll learn about tax lines in a cart and how to retrieve tax lines with the Tax Module.
What are Tax Lines?#
A tax line indicates the tax rate of a line item or a shipping method. The LineItemTaxLine data model represents a line item’s tax line, and the ShippingMethodTaxLine data model represents a shipping method’s tax line.
Tax Inclusivity#
By default, the tax amount is calculated by taking the tax rate from the line item or shipping method’s amount, and then adding them to the item/method’s subtotal.
However, line items and shipping methods have an is_tax_inclusive property that, when enabled, indicates that the item or method’s price already includes taxes.
So, instead of calculating the tax rate and adding it to the item/method’s subtotal, it’s calculated as part of the subtotal.
For example, if a line item's amount is 5000, the tax rate is 10, and tax inclusivity is enabled, the tax amount is 10% of 5000, which is 500, making the unit price of the line item 4500.
Retrieve Tax Lines#
When using the Cart and Tax modules together, you can use the getTaxLines method of the Tax Module’s main service. It retrieves the tax lines for a cart’s line items and shipping methods.
1// retrieve the cart2const cart = await cartModuleService.retrieveCart("cart_123", {3 relations: [4 "items.tax_lines",5 "shipping_methods.tax_lines",6 "shipping_address",7 ],8})9 10// retrieve the tax lines11const taxLines = await taxModuleService.getTaxLines(12 [13 ...(cart.items as TaxableItemDTO[]),14 ...(cart.shipping_methods as TaxableShippingDTO[]),15 ],16 {17 address: {18 ...cart.shipping_address,19 country_code:20 cart.shipping_address.country_code || "us",21 },22 }23)
Then, use the returned tax lines to set the line items and shipping methods’ tax lines:
