This API calculates income tax based on the gross amount and country provided. It takes in the gross amount and country as input and returns the tax amounts for residents and non-residents, as well as the net income amounts for both. The response includes the gross amount, residence tax amount, non-residence tax amount, net resident amount, net non-resident amount, currency, and additional notes. For example, for a gross amount of $12,900 in the United States, the API returns the residence tax amount, non-residence tax amount, net resident amount, net non-resident amount, and additional notes related to tax filing statuses.