I've recently discovered that incorrect ct returns have been filed. The first period was for 2 months in one return and the second return covered 12m I think it should be the other way round. Can we file amended returns for this? Any help gratefully appreciated. Thanks.
You can make amendments with a CT return with your tax return software (or HMRC's).
However, if the CT has been calculated correctly I would just call HMRC CT office and explain the situation. I have had this problem and I called HMRC and told them that I could send them amended returns if they wanted me too, but there would be no change in tax and they told me not to bother!