If customers enter their tariff rate manually, depending on their choices, Connect may, depending on your customer’s energy provider, request you to render a page where they can specify tariff rate surcharges. For example, they might be on a MARKET tariff and will be paying additional brokerage fees or taxes on top.

Surcharges are applied by first adding the fixed fee, then applying the percentage to the result.
The Tariff region (region) property is returned only when the customer is on MARKET tariff and Connect service was unable to automatically detect their market region.