This problem is designed to get you to think about controls that would be effective in a real$-$world setting. The Canada Border Services Agency $($CBSA$)$ receives cash payments for services, fees, and taxes $($e$.$g$.,$ customs duties, excise taxes, taxes on goods and services$)$ at various ports of entry around Canada. Cash includes payments made in liquid cash, by debit or credit cards, and by checks.

a$.$ What types of controls should the CBSA have over its cash receipts?

b$.$ Given the controls that you identified in part $($a$),$ what types of tests of controls or substantive audit procedures should an auditor perform?