**What**
- Selects the correct tax line for an item given a calculation context.
**For later PR**
- Consider optimizations. Some thoughts:
- Even with global sales the number of rates in the DB is not likely to grow beyond ~1000.
- Can large orders with hundreds of items optimize somehow?
- Does it make sense to write a custom SQL query to do this?
- Support combined rate.
**Test cases covered**
The selection of tax rates take the following priority:
1. specific product rules - province
2. specific product type rules - province
3. default province rules
4. specific product rules - country
5. specific product type rules - country
6. default country rules
There are test cases for each of them under the following data seed structure:
### **US**
- **Default Rate**: 2%
- **Sub-Regions**
- CA
- Default Rate: 5%
- Overrides
- Reduced rate (for 3 product ids): 3%
- Reduced rate (for product type): 1%
- NY
- Default rate: 6%
- FL
- Default rate: 4%
- **Overrides**
- None
### **Denmark**
- **Default rate:** 25%
- **Sub-Regions**
- None
- **Overrides**
- None
### **Germany**
- **Default Rate:** 19%
- **Sub-Regions**
- None
- **Overrides:**
- Reduced Rate (for product type) - 7%
### **Canada**
- **Default rate**: 5%
- **Sub-Regions**
- QC
- Default rate: 2%
- Overrides:
- Reduced rate (for same product type as country reduced rate): 1%
- BC
- Default rate: 2%
- **Overrides**
- Reduced rate (for product id) - 3%
- Reduced rate (for product type) - 3.5%
**What**
- Adds Tax rules to allow overrides of tax rates for certain products, product types or shipping options.
**Punted to future PR**
- Currently, the creation methods only support bulk operations. A later PR will include support for singular operations, too.
- It should be possible to add products, types, and shipping options to a tax rate after creating it. Add, remove, update will come in a later PR.
**What**
- Adds a TaxRegion entity.
**For context: High-level design of the Tax module**
- A TaxRegion scopes tax rates to a geographical place.
- You can define tax regions on two levels: country-level, province-level (this corresponds to state in US contexts)
- Each Tax Region can have a default Tax Rate.
- [not yet done] - Each Tax Region can also have granularly defined tax rates for different products and shipping rates. For example, California can have a base rate for default products, but a reduced rate for groceries.
- Tax Rates specify if they can be combined with other rates - it's always the lowest level rate that wins.
The above allows a merchant to define their tax settings along the lines of this:
- Denmark (Region)
- Default rate: 25% (TaxRate)
- Germany (Region)
- Default rate: 19% (TaxRate)
- Reduced rate (books): 9% (TaxRate w. rule)
- United States (Region)
- Default rate: 0% (TaxRate)
- California: (Region)
- Default rate: 7.25% (TaxRate)
- Arkansas: (Region)
- Default rate: 6.5%
- Reduced rate (groceries): 0.125% (TaxRate w. rule)
The TaxModule can then receive a list of products and the shipping address to determine what tax rates apply to the line items.
