Determination of value clarifies supplier options and prescribed methods for computing taxable value under GST rules. For money changing and foreign currency services a supplier may elect either a reference rate method-calculating the difference between buying/selling rates and the Reserve Bank reference rate multiplied by currency units, with specified fallbacks when reference rates are unavailable or when neither currency is Indian Rupees-or a deemed value slab method prescribing percentage or fixed amounts by transaction bands; the chosen option, if exercised, must be retained for the remainder of the financial year. Other prescribed deemed values include percentages of basic fare for air travel agent services, specified proportions of life insurance premium, margin based valuation for second hand goods where no input tax credit was availed, and money value for redeemable tokens or vouchers.