Retailers are reminded that VAT will go up from 17.5% to 20% on January 4. Store owners will have a four-week window after the changeover date to amend shelf labels, but they are required to display a notice informing customers that prices advertised may differ from those charged at the counter.

This is the third time VAT will have changed in the past three years. In 2009 it dropped from 17.5% to 15%, and then changed again in 2010 when the rate returned to 17.5%.

This year's January 4 changeover date has been welcomed by retailers, as it offers some leeway over the busy Christmas season.

The rise earlier this year caused chaos as store owners had to alter the prices of all VAT-affected products by January 1, forcing them to work extra hours over the holiday period and call in additional staff to help them out, leading to higher wage bills.

Last year Sylvia Winter of Creaton Village Stores in Northamptonshire had to spend her evenings working to ensure the changes were made. "For the last VAT change we had to work extra hours after the shop closed to change more than 1,000 products in time for New Year's Day," she said. "At least this year we have a couple of days' grace after the new year so we don't have to rush it."

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