There can be no late filing penalty for corporation tax returns if the return is filed with HMRC by the date on which the accounts are due at Companies House.

There have been cases where HMRC have incorrectly raised a penalties based on tax return due dates being earlier than Companies House accounts due dates.   If this is appealed on the basis that the tax return cannot be due before the accounts then HMRC will remove this penalty.

More details at:

http://www.hmrc.gov.uk/manuals/commanual/com100010.htm