Kelkoo, a price comparison site, in conjunction with the Centre for Retail Research, calculated that consumers are likely to spend £537 million online today, nicknamed by some retailers as Mega or Manic Monday, up 29 per cent on the equivalent day last year.
Visa said it expects UK consumers to defy fears over the recession and any resulting job cuts by splashing out 5.5 per cent more this year than they did during 2009's Mega Monday.
The Monday closest to December occurs shortly after pay day for many consumers and has consequently been the busiest day for e-tailers for the last two years.
Visa's predictions, which are based on current spending data as well as previous years' Christmas spending trends, are considered accurate because more than £1 in every £4 spent in the UK is on a Visa card.
Online retailers Amazon and Play.com, among others, believe Mega Monday will fall a week later on December 6th.
Play.com predicts that 1,200 orders will be placed per minute during the busiest periods during the day but, rather than buy their gifts at lunchtime, shoppers will wait until they get home to splash out – with 9.30pm becoming the peak purchase time.
Traditionally consumers window shop and do their research over the weekend, before using the internet access at work on the Monday to order. According to Ofcom, the proportion of households with a broadband connection has also increased from 52 per cent three years ago, to 71 per cent today.
Steve Perry, commercial director, Visa Europe said: “Shopping online is now a natural part of the gift-buying process for consumers and a key part of Christmas sales strategy for retailers. The combination of monthly salaries being paid and people taking delivery times into consideration should combine to deliver a record day for internet shopping.
Richard Stables, the chief executive of Kelkoo, added: “Trading conditions remain challenging on the High Street, and in a bid to entice consumers to shop now and drive up sales in the run up to Christmas, a number of retailers have already announced early discounts.
"The impending VAT increase is also expected to provide an additional catalyst for consumer spending this Christmas, with every household in the country facing a steeper VAT bill, amounting to an additional £1.16 per day."