Planning expensive Diwali purchases? Paying upfront could help you secure additional discounts, while no-cost EMI can spread payments. Compare processing fees, GST, cashback and credit card. Planning Diwali shopping with a credit card EMI? Check five hidden costs of no-cost EMI offers, including processing fees, GST on interest, lost instant discounts, foreclosure charges and credit. Cash Discount vs No-Cost EMI: Diwali is a popular time to buy new things.