The UK government has an excellent on-line process for allowing its citizens to upload their tax returns except on one day of the year- 31st January.
The rules around self-assessment mean that the citizen must have provided a tax return for the previous tax year by the 31st January. As the year ends on the previous April you would think that would provide enough time...
There is a £100 fine for not hitting the date and this seems to be the issue. As with each year before the rush to get tax returns in has taken down the web site - See here.
This has meant the deadline has been extended by a day...
The system is part of the government ecommerce service, Government Gateway, which was updated last October to cope with future growth and to allow for usage peaks such as tax-filing deadlines.
Maybe not quite enough......