Question the first: You are presumably the bookkeeper for this company - so it might help forum members if you offer some insight into your background and abilities. E.g. are you solely employed by this company, or are you self employed and they're a client (I'm guessing an employee judging by your phrasing), and so on.

Question the second: What version of Sage Instant? This is a very important question, because different people use different versions, which have different facilities - so when someone answers/offers help, they might suggest things that your version doesn't allow you to do.

Those aside, as I've just said to someone else: Start by having a nice, relaxing cup of tea and - most importantly - don't panic.

Now a new set of questions:

Have you told Sage to "reconcile" or "flag" the transactions on that VAT return yet, or is it still live? (i.e. does it stored in the list of VAT returns, or do you have to run it and enter the dates) ? If you are still at the stage where you have to run it and enter the dates, that means you still have time to fix it if there is definitely a problem.

If you *have* 'reconciled' the return, do you have a backup from immediately before doing so (and related, have you input many transactions since)? (This determines whether it is practical to go back to that point, or whether that would be too much work).

Start with these questions, and someone else will hopefully pick the thread up later (I'm not at a Windows computer today, so any comments I make will be from memory rather than looking at a real version of Sage)

I was half thinking that, and half thinking about Emma's comment about the year end being done, and the possibility of one or more journals being posted with the wrong T-code.

That's particularly odd.

If it was a T-code problem on the year end journals (an incorrect setting*), I'd expect it to be consistent across the debits and credits - so it would affect the inputs as well as the outputs.

* There was a version of Sage which did have an incorrect setting along these lines, straight out of the box - but it was a VERY long time ago, so I'd be surprised if it's the same problem now (plus, it would affect all of the figures, as I said). I saw it at a small number of different places, some of which I'd been called in to investigate a problem along these lines.

Another possibility: The payment after the last VAT return - double check that it wasn't incorrectly input as T0 instead of T9 (assuming the usual defaults). This used to be a common mistake I saw when called to look at problem figures. (I think it largely stopped when Sage added the ability to enter the payment from the tasks button on the return itself).

Okay - so what about the other questions:

"Have you told Sage to "reconcile" or "flag" the transactions on that VAT return yet, or is it still live? (i.e. does it stored in the list of VAT returns, or do you have to run it and enter the dates) ? If you are still at the stage where you have to run it and enter the dates, that means you still have time to fix it if there is definitely a problem.

If you *have* 'reconciled' the return, do you have a backup from immediately before doing so (and related, have you input many transactions since)? (This determines whether it is practical to go back to that point, or whether that would be too much work)."