The first thing to watch out for in such schemes is blackout dates. These are the periods when no discounts apply, be it holidays or peak season. The offer could also be limited to a certain time of the week, say mid-week or the weekend. If it's the former, you have to consider your chances of getting leave from work. On the other hand, weekends typically cost more. Remember that advance purchase is mandatory in most such deals.
Any cash-back offer typically comes in the form of a gift voucher for future use. However, on the rare occasion that you get an instant discount, there are several caveats to watch out for. If the payment is not received by the travel provider within the stipulated time frame, you will be automatically charged the regular brochure price. In the case of flights, the cash-back amount is usually calculated on the base fare, which is, sadly, the smallest component of the fare break-up.The advertised price is often the starting price for budget accommodation and from an airport/railhead closest to the destination. In addition, it may not factor in charges like taxes and visa fees. These hike the package cost, particularly if you are flying out of India from select airports. Lastly, though children sharing a room with parents are offered free stay or a discounted rate, an adult with a child may have to pay the twin-sharing rate.
Sounds like a steal, right? Such an offer would be worth your while, and money, only if it is valid for all airlines and hotels across categories and anywhere in the world. Most importantly, it should not come with a narrow validity window, say, 10 days. Too bad that most such deals are sure to have at least one such caveat. Also, say goodbye to the flexibility of modifying plans.