Notional Payroll Payments

Summary:

An employer makes a payment outside the system, but the statutory deductions need to be processed through payroll. What is the best way to do that?

Content (please ensure you mask any confidential information):

Employee expenses are processed using an external system that doesn't integrate with HCM. Some of these expenses should be taxable and NIable.

When this happens, a notional payment needs to go through payroll. i.e. no payment is produced, but Taxable Pay and NIable Pay need to be increased. What is the best way to build this in Cloud Payroll?

I have some ideas, but each one has its drawbacks