Solidus's taxation system supports both sales- and VAT-style taxes. You can use tax rates, tax categories, and the built-in tax calculator to handle your store's tax logic. Solidus uses the Spree::Adjustment model to apply taxes to orders. This way, there can be multiple tax adjustments applied to each order.

Using adjustments helps account for some of the complexities of tax, especially if a store sells internationally:

  • Orders may include products with different tax categories or rates.
  • Shipments may require special calculations if you are shipping to or from locations where there are specific taxation rules for shipments.
  • Taxes may or may not be included in a product's price depending on a country's taxation rules.

Solidus uses the Spree::TaxCategory and Spree::TaxRate models to specify the rules for how tax adjustments are calculated. Tax adjustments are created for each line item in an order.

See the Order taxation section for an overview of the order taxation process.

Tax categories

Tax categories can be used to ensure particular products are taxed as required. For example, if your business is based in Minnesota, you need to charge tax on tech products but do not need to charge tax on clothing. You could set up two tax categories, Clothing and Tech which you would apply to products of either type.

By default, new products do not have a set tax category. Administrators can set the tax category while creating the product or set it later while editing the product.

Tax rates

Tax rates define the amount of tax that should be charged on items. You might configure different tax rates for different zones and tax categories, or even for specific dates. You could also create more complex tax rates with a custom tax calculator.

In Solidus, a tax rate consists of at least four values:

  • The descriptive name for the tax rate. For example, "Minnesota Sales Tax" for a Minnesota state tax rate.
  • The zone that the tax rate should apply to.
  • The rate (in the form of a percentage of the price).
  • The "Included in price" boolean. This indicates whether the tax is included in the price (for value-added taxes) or added to the price (U.S. taxes).

Solidus calculates tax based on the matching tax rate(s) for the order's tax address .

Tax addresses

If an order's tax_address falls within a specific zone, the tax rates that you have configured would apply for all the line items and shipments in that zone that have a matching tax category.

By default, the tax_address used for orders is the customer's shipping address. This is how most tax jurisdictions require taxes to be calculated. However, you can configure your store to globally use customer billing addresses instead in any initializer file inside the config/initializers/ directory:

      Spree::Config[:tax_using_ship_address] = true


Use Spree::TaxLocation as the tax address

An order's tax_address can – through duck typing – be a Spree::Tax::TaxLocation instead of the shipping address. The tax location is computed from the store's Spree.config.cart_tax_country_iso setting.

Note that you can only trust the tax address if it has a country. The other address fields might be empty or raise errors.

Sales tax and value-added tax

In ecommerce, consumption tax either takes the form of sales tax or value-added tax. Some countries use other names for their taxes, but generally all modern consumption taxes would be considered one of these two types.

Solidus's models support both types of taxes. In the case of a product or shipment:

  • Sales tax is calculated as additional taxes on top of the listed price. (U.S.-style taxation.)
  • Value-added tax (VAT) is calculated as included in the listed price. Solidus lists all VAT amounts below the item total on checkout summary pages. For more information about VAT, see Value-added tax (VAT) .

Tax in the United States

Note that sales tax in the United States can get exceptionally complex. Each state, county, and municipality might have a different tax rate.

If you intend to ship products between states, and your store is based in the United States, we recommend that you use an external service like Avatax or Tax Cloud to automate your U.S. tax rates. Solidus has extensions for both of these services: solidus_avatax_certified and solidus_tax_cloud .

Order taxation

Once the order has a tax_address specified, tax can be calculated for all of the line items and shipments associated with a Spree::Order:

Note that any promotional adjustments are applied before tax adjustments. This is to comply with tax regulations for value-added taxation as outlined by the Government of the United Kingdom and for sales tax as outlined by the California State Board of Equalization .

  1. Solidus iterates over all of the order's line items. It selects the tax rates that match each item's tax category.
  2. For each line item, the tax rate (a percentage value) is multiplied with the item's amount value. (price ✕ quantity ➖ promotions.)
  3. The calculated amounts are stored in a Spree::Adjustment object that is associated with the order's ID.
  4. The line item's included_tax_total or additional_tax_total are updated. (If the Spree::TaxRate's included_in_price value is set to true, Solidus uses the included_tax_total column to store the sum of VAT-style taxes. Otherwise, it uses the additional_tax_total to store the sum of sales tax-style taxes.)
  5. The same process is executed on the order's Spree::Shipments.
  6. The sum of the included_tax_total and additional_tax_total on all line items and shipments a stored in the order's included_tax_total and additional_tax_total values.

The included_tax_total column does not affect the order's total, while the additional_tax_total does.

Every time an order is changed, the taxation system checks whether tax adjustments need to be changed and updates all of the taxation-relevant totals.

See the taxation integration spec for more information on Solidus's taxation system.


Solidus is an open source platform supported by the community. We encourage everyone using Solidus to contribute back to the documentation and the code.

If you’re interested in contributing to the docs, get started with the contributing guidelines. If you see something that needs fixing and can’t do it yourself, please send us an email.