Being a T4 employee means you are officially employed by Raise while on assignment and as such, taxes and other payroll deductions will be automatically withheld from your paycheck.
This simplifies your tax filing process since Raise handles the deductions for income tax, Canada Pension Plan (CPP) contributions, and Employment Insurance (EI) premiums from your pay.
At the end of the year, Raise will provide you a T4 slip, which reports your earnings and deductions. You use this form to file your income tax return.