My trade debtors balance in the balance sheet doesn't match the total balance shown on the aged debtors report

No problem!

I assumed we’d included credit balances on the ageing reports some time back and having now just checked I can see they are present.

One thing that may cause some confusion here is if the client does not have any outstanding invoices, then there will be no row on this report and consequently no credit balance shown, even though they may have one but minus any outstanding invoices.

The full list of clients with credit balances can still be isolated in the main client list. We’ll consider changing the ageing report to include this too, time permitting.