One of the worst IT disasters in years has been steadily unfolding for HMRC. Tax agents are unable to electronically file perfectly valid self assessment forms because of hundreds of errors in HMRC’s new back-end systems.

HMRC has had to publish an extensive list of work-arounds to help with the many validation errors that its new systems are generating during online filing of its self assessment forms - see hmrc.gov.uk/ebu/se-indi.pdf.

The current list is 19 pages long with more than 71 items listed. It has been suggested that HMRC is reluctant to add new problems to the list in case it opens up too many grounds for appeal.

This year, HMRC radically changed the layout of its self assessment forms and, under Lord Carter’s recommendations, changed its back-end systems to streamline electronic filing.

Like many experiences in the past, HMRC did not allow enough time for testing of its systems both internally (with its outsourced partner) and with third-party software developers. It did not effectively communicate the changes to the forms with tax agents who are finding it difficult to understand the new layout.

These problems have resulted in huge numbers of callers blocking its support lines and those of the software developers.

The bulk of the validation errors relate to the new Schematron validation tool used by HMRC. This is rejecting perfectly valid online entries or insisting fields are mandatory when they are not.

These are content errors, which only started to show up when tax agents started filing real data. The sample test data that was used initially to validate the systems did not show up these errors.

One would have thought that with so much egg on its face, HMRC would have taken dramatic action to fix these problems in as short timescale as possible - but no. The HMRC website shows the status on each problem will be reviewed/enhanced in year 2008/09 - so no urgency there, then.

So what can tax agents do in the meantime? They are presently being asked to undertake work-arounds and contact tax offices directly. Luckily, it’s not the silly season for self assessment e-filing yet - that is January next year. Perhaps some of these errors will be sorted out by then.

When will HMRC take a responsible view of system changes? It’s as if common practice in delivering IT systems does not apply to the government

Dennis Keeling is a software analyst and was CEO of BASDA and chairman of its taxation special interest group