A small but significant slice of sales made via safe shopping online are being lost because of problems with expired codes that earn customers a discount, according to a report from SmarterClick.com.

Analysts argue that almost half a million potential purchases are abandoned due to codes which are past their usable period, meaning that shoppers can become disillusioned with the whole process and even have a worse opinion of the retailer as a result.

In the case of an in-date code being encountered and acted upon, the conversion rate sits at an impressive 55 per cent, meaning that more than half of people who get to the checkout and are able to redeem a discount will go through with the transaction.

However, if a code is out of date, just 14 per cent of people will complete the purchase, meaning that there is a large margin between the two circumstances in terms of sales success.

Close to four per cent of all people who visit retail sites in the UK are led to the site in question because they have found a voucher code elsewhere online. It is easy to see that old codes which do not work could be a real bugbear for any consumer from within this group who attempts to make a purchase.

The size of the retailer has an impact on the number of attempted uses of outdated codes each month, with some of the biggest e-commerce sites receiving over 50,000 instances of old codes being entered at the checkout.

While consumers clearly have a familiarity with the concept of voucher codes in the modern era of online shopping, it is still frustrating to find that a code is no longer functional after going through the process of adding items to a basket and reaching the checkout, so steps to address this would be welcomed.