Bug stops mixed PDF/iXBRL CT600 submissions

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John Stokdyk
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AccountingWEB members have flagged up a minor bug in HMRC’s Corporation Tax efiling mechanism that blocks submissions that include both PDF and iXBRL format files for computations and accounts.

In an Any Answers thread Sudipta Moore of  Moore Accountancy explained that HMRC’s online filing system rejected a CT600 and computations that were accompanied by a PDF attachments for the year to 10 June. HMRC’s system responded with the message: “X ERROR: If the period 'To' date is on or after 01/04/2010 and the date of submission is on or after 01/04/2011, the Accounts must be submitted in InlineXBRL format.”

HMRC’s Corporation Tax service issue page currently offers the clarification that its free to use Company Tax Return filing product will not allow submission of the return if the accounts and computations files are not both in iXBRL or PDF.  The user can submit the return so long as both the accounts and computations files are in the same format. 

A spokesman told AccountingWEB.co.uk HMRC plans to upgrade the mechanism in October to allow submission of a mixed submission of iXBRL and PDF files for the period leading up to April 2011, when only iXBRL attachments will be accepted.

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26th Sep 2010 14:13


might it be that HMRC is so dependent on short term contractors for its IT solutions that they almost have to reinvent the wheel everytime something goes wrong - not enough continuity 

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27th Sep 2010 09:09

Not sure if I agree with you

I don't think that the role of short-term contractors is the core problem with HMRC's IT services, I think it's more to do with the nature of the department's outsourced ASPIRE IT contract, where a certain level of service has been agreed over a 10-year period (for a starting price of £10bn that has gone up significantly since it was first agreed).

Agreeing project specifications with a third party introduces one element of disconnection, and the way these things work any engineering change will have to be agreed separately and paid on top. There's almost an incentive for the contractors to go ahead with half-baked specs, as they can then charge more to come back and carry out the fixes.

My guess is that the transitional niceties of mandatory iXBRL filing were missed out at the original development stage (we have to remember this is a department and IT outfit with a huge amount of work on its plate) and the decision was taken to go live anyway because of the tightness of the April 2011 deadline. Down at the individual contractor level I think people will typically be given discreet projects to work on under the direction of the ASPIRE/HMRC project managers, so they're just a symptom of the structural problems affecting HMRC's IT systems rather than the cause.

For a background illustration of how things work in this part of HMRC, have a look at the NAO report into the 2009-10 annual accounts, which details how the new National Insurance and PAYE Service (NPS) project went off the rails through weak QA and project management during 2008-10. That episode required so much remedial work that I am sure it will have affected work on other IT projects such as the CT online system.

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27th Sep 2010 09:46


Can they get anything right? Yet they want to force us to use online filing - even though they cope!!!

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By cfield
27th Sep 2010 11:42

Mixed PDF and iXBRL submissions

I was at an ACCA seminar last weekend where a team from the Revenue were explaining iXBRL. They told us they could still read any items that couldn't be tagged (ie those not in the relevant taxonomies such as lawsuit provisions) from the attached PDF document, so I came away thinking that you needed to submit both. Slightly confusing as I thought that was what they were trying to move away from. But if PDF files will not be accepted once iXBRL becomes mandatory, then how are they going to read non-taggable items? The team from the Revenue said that they would even be able to see logos in their human readable form. I don't see how that is possible without a PDF file. Hopefully someone will be able to clarify this as it will affect anyone using conversion software or the free HMRC service rather than FAP software (Final Accounts Production).


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27th Sep 2010 17:48



An iXBRL document is an html document (like web pages on websites) with various figures and text "tagged" so that they can be read by computer. Not every figure needs to be tagged - tagging does not affect what a human operator can see, only what a computer can extract from the document. PDFs are not necessary for this. The need for PDF is just until you can produce the necessary documents as iXBRL.

David Forbes

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By cfield
27th Sep 2010 18:06

PDF query

Thanks for that David. It was the fact they kept referring to PDFs that confused me.


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