How to work out your real take-home pay from your tax return

Every expense-splitting calculator opens with the same question: “What is your after-tax income?” Almost nobody knows.

That is not carelessness. The number is genuinely hard to get at, and every convenient shortcut gives the wrong answer.

Why your paycheque is not enough

Multiplying your net pay by 26 fails for several reasons at once:

• Your contributions stop partway through the year. Once you hit the CPP, QPP or EI maximum, your deductions drop. Your last cheques of the year are bigger than your first.
• You did not pay exactly the right tax. A refund or a balance owing is proof that the amounts withheld were an estimate.
• Bonuses, overtime and unpaid leave follow no steady rhythm.

Why box 22 is the wrong number

Box 22 on your T4 shows tax withheld, not tax paid. If you got a $2,000 refund, you overpaid by $2,000 during the year — that is not a cost, it is money that came back.

The figure that matters is what you actually owed, and it lives elsewhere on the return.

The formula

One formula works everywhere in Canada, whether you are employed, self-employed, or both:

take-home = line 15000        total income
          − line 43500        total payable
          − TP-1 line 450     Québec only
          + line 44000        Québec abatement, Québec only
          − payroll deductions   T4 boxes only

Line 15000 — total income

Page 3 of your federal return. Everything you earned before deductions.

Line 43500 — total payable

This is the crux. The line contains:

Line	What it is
42000	Net federal tax
42100	CPP payable on self-employment
42120	EI premiums payable on self-employment
42200	Social benefits repayment
42800	Provincial or territorial tax

Two consequences worth noticing:

Outside Québec, your provincial tax is already in there. There is nothing further to subtract — no second return exists.

If you are self-employed, your CPP is already in there too. Subtracting it again is the most expensive mistake in this calculation.

TP-1 line 450 — Québec only

Québec collects its own income tax on a separate return. Line 450 is your whole Québec bill, and it already includes QPP (line 445), QPIP (439), the health services fund (446) and the prescription drug insurance premium (447).

Line 44000 — the Québec abatement

If you are a Québec resident and you skip this line, your calculation over-subtracts federal tax, usually by more than a thousand dollars. Full explanation here.

T4 boxes — and nothing else

These are the only contributions to subtract, because they are the only ones not already inside a “total payable” line:

• Box 17 and 17A (or 16 and 16A outside Québec) — QPP or CPP
• Box 18 — employment insurance
• Box 55 — QPIP, in Québec
• Box 20 — your registered pension plan contributions
• Box 44 — union dues

Two adjustments worth understanding

Your RRSP is never added back. You contributed out of money that is already inside your take-home. Adding it would count the same dollar twice.

Your pension contributions (box 20) probably should be. That is savings into an asset you own, not spending. If you are comparing two people and only one has a pension plan, treating those contributions as income they never had makes them look poorer than they are. Our calculator adds them back by default, and you can switch it off.

A worked example

A Québec employee with $85,000 of total income:

Total income (15000)	$85,000.00
Total payable (43500)	− $9,900.00
Total Québec payable (450)	− $10,800.00
Québec abatement (44000)	+ $1,633.50
T4 payroll deductions	− $10,615.77
Pension contributions added back	+ $4,000.00
Take-home	$59,317.73

Without the abatement the same calculation gives $57,684.23 — $1,633.50 poorer than reality.

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