Lucas works weekdays at an Ottawa office and picks up weekend shifts at a café. Both pay statements show income tax deductions. He expects that to settle everything.
The difficulty is that neither payroll automatically knows the other job's earnings. His tax return brings both incomes together.
Compare the whole year
Lucas lists his gross earnings and income tax withheld from each job. He uses the latest pay statements to estimate the remaining months, allowing for changing hours and any bonus. Take-home pay alone cannot show whether enough tax has been deducted.
A second job does not have a separate final tax rate. The combined annual income, deductions and credits determine the result. A small weekend paycheque can therefore create additional tax that its own payroll calculation does not fully cover.
Check the credits on both TD1 forms
Personal tax credits generally should not be claimed twice at concurrent employers. If Lucas has already claimed them with one employer and his total income exceeds those credits, the CRA's multiple-employer instructions tell him to check the relevant box on the other TD1 and enter zero on line 13.
That instruction concerns simultaneous employment. Changing employers partway through a year deserves a separate review rather than automatically copying the same answer.
Make the adjustment while there are paydays left
Lucas can request extra income tax deductions through his TD1. A projection using both jobs helps him choose an amount; an arbitrary extra $10 per pay may accomplish very little.
He keeps a copy of the updated forms and checks the next pay statement. At filing time, he reports both T4 slips. Additional withholding changes when he pays tax, not the income he must report or the final calculation.
Read when to update a TD1 before sending the forms to payroll.
