Firstly, in legal terms you should be able to do this as long as the invoice in question is below a certain value. Please see: http://customs.hmrc.gov.uk/channelsPortalWebApp/channelsPortalWebApp.portal?_
4.2 Methods for correcting errors
There are two methods for correcting errors:
Method 1: for errors of a net value that do not exceed Â£10,000, or errors of a net value between Â£10,000 and Â£50,000 that do not exceed the limit described in paragraph 4.3
Method 2: for errors of a net value between Â£10,000 and Â£50,000 that exceed the limit in paragraph 4.3, or for net errors greater than Â£50,000.00, or if you so choose, for errors of any size.
As long as all that is OK, In Clear Books you will need to:
When you generate your next VAT return you will see that there is an option to 'View report of transactions excluded or not currently on a VAT return. Do this to ensure you have not omitted any transactions'.
Here you will be able to select the right criteria, including date range for the missing invoice. Choose the invoice you want and add it on.
I hope that this is nice and clear. If you need to know anything else, please let me know.