This means you are doing a business return?This means Sched C, since any other business is already late filing, unless you put the 1065/1120/1120S on extension.

Do you know who does and does not get paid through payroll, so that you are expensing the right values? Do you understand employer taxes? Do you understand which benefits are payroll and which additions are not payroll expense?

It concerns me for your client. You might want some mentoring.