How to record refund from supplier paid in previous period

I am filing a tax return for a company with no taxable income in the year. There are no expenses apart from c£600 admin expenses. There was a refund received from a previous supplier c£3k. I cannot find the appropriate box for this on the CT return - it is not income, nor will it let me input a negative number on the expenses? Micro accounts so using the online accounts and tax filing tool. Please advise?

Hi,
This should be recorded in the accounts, not the tax return, so would not be recorded in any box.
Thankyou.