Hi,

Use Projects,

Can also use department as different companies.

Provided that each employee works exclusively for exactly one company, it's possible to use departments.  Once you set up employees for a Department, the book-keeping entries to track expenses are more automatic.  If you're not currently using Departments, this may also add some complexity.

Because Projects sort of sit outside the transaction data, they provide useful tracking without adding complexity.  On the other hand, the data entry by employee has to be done with each employee's hours allocated to the particular company they worked for.  Projects can be allocated or tracked by hours or by percentage.

There's really no need to track anything but the wage expense and the employer's share of WCB,  EI and CPP contributions.  The rest of the remittance comes out of wage expense, so the inter-company amount is the total of those expenses for the hours worked.