You do not need to be an accountant to ask good questions about your numbers. Five basic checks tell you a lot about how reliable a report is.
1. Does the bank reconcile?
Ask for the bank reconciliation for each account, up to the latest date. Unreconciled items older than a month need an explanation.
2. Do the subledgers agree with the ledger?
The list of customers who owe you should add up to the receivables figure in the books. Same for suppliers and payables. If they do not match, something is posted outside the system.
3. Is anyone checking duplicates?
Duplicate vendor payments and duplicate invoice numbers are common errors and easy to test for. Ask whether a check exists and when it was last run.
4. Who can create a vendor and who can pay one?
Where the same person can add a vendor, raise an invoice and release payment, there is a control gap. Separation of duties is basic and powerful.
5. Are the unusual items explained?
Large round-figure entries, entries just before month end, journal entries without a description and expenses posted to odd accounts deserve a one-line explanation each.
These checks do not prove anything is wrong. They show whether anyone is looking.
If several of these answers are unclear, that is useful information in itself. It tells you where to start tightening the process.