But these schemes have earned Which? members some healthy returns over the years.
We know because every month we survey thousands of Which? members to find out how they save money on bills or everyday purchases.
Here, we show you the tips and tricks members told us about when asked how they earn cashback on their spending.
Cash back credit cards reward you for spending, by paying a small percentage of your overall spend back onto your card as credit.
Making the most of these credit cards takes commitment and control. The more you spend on your card, the more cashback you’ll earn, but unless you can pay off your balance in full each month, the interest you incur will outweigh your returns.
Which? members who told us they use cash back credit cards earned £90 a year on average, although some reported making more than £500 a year.
The Which? Money Compare credit card tables let you search hundreds of cards from providers large and small to choose a great deal based on quality of service as well as cost and benefits.
Some credit cards come with eye-catching retail reward schemes.
We heard from Which? members who had earned vouchers at Tesco, M&S, Waitrose and John Lewis by spending on credit cards provided by these retailers.
Others told us they were able to bag a bargain holiday by building up air miles on a rewards credit card.
Our survey’s respondents saved an average of £100 per year by taking advantage of these schemes.
Cashback websites reward you for completing online shopping orders through their retail partners – and are very popular among Which? members.
You can find cashback on a variety of purchases, but insurance or telecoms products tend to offer the most generous payout. One member told us how he saved £70 on a Virgin Media TV, phone and broadband bundle by buying it through topcashback.co.uk.
Another said she had earned £1,400 through quidco.com by checking the website before making all her online purchases in the last few years.
The average Which? member who told us they used cashback sites was able to save around £100 per year.
A number of Which? members told us they save up loyalty points with their local supermarket throughout the year, in order to accrue enough for a big Christmas shop.
Many members said they had taken advantage of the Tesco Clubcard Boost scheme to multiply the value of their points, or taken advantage of the supermarket’s promotions to double the value of points in time for Christmas.
With some loyalty cards, you can spend points with associated retailer partners to multiply their value. For example, one savvy member told she was able to use her Tesco Clubcard and Nectar points to pay for four people to go to Legoland and Chessington.
On average, Which? members using loyalty cards saved around £60 per year.
Read more: http://www.which.co.uk/news/2016/02/how-to-save-money-by-earning-cashback–432630/