what do you mean by checking the accounts that were submitted match the paperwork that is on file?
Basically, your wife would have had to submit a tax declaration. If they're making an inspection of her business they would want to see that the figures match with the invoices/bills (whether issued or received).
what are we talking here? 5,000 or less?
Yes, less than that, unless the amount of any proven misdeclaration are very large. What was the legal basis of the business - a limited company or self-employed?
surely it's the same for my accounts also?
That's something they'd only do if they couldnt get any money they wanted from your wife, it isnt a routine thing - and remember, there may not be anything to collect, especially if they have no evidence of cash-in-hand stuff. It also depends on the legal basis of the business, as above.
BTW, which part of KSA were you in? I did a stint in KSA a few years ago but now go to Iraq every month instead.,