New Delhi, Sept. 8 -- Nothing focuses the mind like a commonly felt external threat. Suddenly, the quagmire that had developed in India's goods and services tax (GST) regime has been cleaned up. Even though the GST Council had begun to discuss changes some time ago, those discussions were gridlocked. Voila, just this week, we have GST rate simplification, thanks to US President Donald Trump's 50% effective tariff on India.

GST rate simplification was long overdue. Rates had been absurdly high and fiendishly convoluted. An identifiable part of a single finished product could have a different rate from the rest of the product, resulting in several memes on social media. In some sectors like textiles, there was even a 'tax inversion,' meani...