HM Revenue & Customs has been forced to extend the deadline for filing self-assessment tax returns online after its website crashed due to the number of people trying to file their returns before the 31 January deadline.
During the morning and early afternoon of Thursday, users trying to access the self-assessment online section of HM Revenue & Customs' (HMRC's) website were confronted with the message: "Online service temporarily unavailable".
A reader of ZDNet.co.uk sister site silicon.com, unable to get onto the self-assessment site, contacted the HMRC helpline and was told the problem was due to the high volume of people trying to access the service.
Prior to the website's crash, anyone who failed to file their tax return online before midnight on 31 January faced a £100 penalty, but HMRC has now extended the deadline.
An HMRC spokesman said the organisation takes disruption of any service very seriously and, to reflect this, the self-assessment deadline has been extended by 24 hours to midnight on 1 February.
The spokesman said: "HMRC's self-assessment online filing service has experienced technical difficulties this morning which have meant that some taxpayers have experienced difficulties filing online. The system is now rapidly returning to normal levels of service. A record number of 3.6 million taxpayers have already successfully filed online, with 104,000 filing today."
In 2007, around three million people used the website to submit their tax return self-assessments.
The system is part of the government e-commerce service, Government Gateway, which was updated last October to cope with future growth and to allow for usage peaks, such as tax-filing deadlines.