HMRC shuts phone lines to tackle post pile HMRC is closing phone lines for three days this month to deal with a backlog of post built up during the pandemic. VAT and corporation tax lines were closed yesterday and will be shut again for the next two Fridays as call centre staff are switched to mail-opening duty. This comes amid a backlog which means those who wrote to HMRC last week can expect a reply by June 23. The tax office says it will look to address this and aims to be back to pre-pandemic service levels by April.