E-mails between the National Audit Office and HM Revenue and Customs officals have been released by ministers
On Nick Robinson's newsblog, you can view a PDF of the e-mail exchanges, as well as letters from the National Audit Office.
You will need Adobe Acrobat to open a PDF.
You can download Adobe from the offical site.
The final document is a briefting for Chancellor Alistair Darling.