Line 23400 on your T1 return is your net income before adjustments. It is the subtotal you get after subtracting eligible deductions from your total income on Line 15000, but before one final step: the social benefits repayment on Line 23500. The Canada Revenue Agency uses the Line 23400 figure to decide whether you owe back part of your Old Age Security or Employment Insurance benefits, which is why it sits on the return as its own line rather than being folded into your final net income.
Where Line 23400 Sits on Your T1 Return
Your return runs through a sequence of income figures, and each one does a different job. Line 23400 is an intermediate stop between total income and final net income.
- Line 15000 is your total income from all sources before any deductions.
- Line 23400 is total income minus your eligible deductions from Lines 20700 through 23400.
- Line 23500 is the social benefits repayment, calculated from your Line 23400 figure.
- Line 23600 is your final net income: Line 23400 minus the repayment on Line 23500.
- Line 26000 is your taxable income, after further deductions like loss carryovers.
The line exists so the CRA can calculate your social benefits repayment before finalizing your net income. Without an intermediate figure, the repayment math would loop back on itself.
How Line 23400 Is Calculated
Start with Line 15000, then subtract every eligible deduction reported between Lines 20700 and 23400. Whatever is left is your net income before adjustments.1Canada Revenue Agency. Line 23600 – Net Income
The deductions that feed into Line 23400 cover a wide range of expenses. The common ones include:
- Registered Pension Plan contributions on Line 20700, taken from Box 20 of your T4 slip.2Canada Revenue Agency. T4 Slip – Statement of Remuneration Paid
- RRSP contributions on Line 20800, limited to the room shown on your prior-year Notice of Assessment.
- Union and professional dues on Line 21200, from Box 44 of your T4.
- Child care expenses on Line 21400, generally claimed by the lower-income spouse.3Canada.ca. Line 21400 – Child Care Expenses – How to Claim
- Moving expenses on Line 21900, if the new home is at least 40 kilometres closer to work or school by the shortest public route.4Canada Revenue Agency. Line 21900 – Moving Expenses
- Deductible support payments on Line 22000, paid under a written agreement or court order.5Canada Revenue Agency. Amount You Can Claim or Report – Personal Income Tax
- Carrying charges and interest on money borrowed to earn investment income, on Line 22100.6Canada Revenue Agency. Line 22100 – Carrying Charges, Interest Expenses, and Other Expenses
- Employment expenses on Line 22900, but only if your employer signed a T2200 certifying you had to pay them and you completed Form T777.7Canada Revenue Agency. Employment Expenses 2025
Tax software handles the arithmetic once your slips and receipts are entered. Errors at the deduction stage cascade downward, though, changing everything from your social benefits repayment to your final tax owing.
Line 23400 vs. Line 23600
The two lines sit one step apart and cause plenty of confusion. Line 23400 is your net income before the social benefits repayment. Line 23600 is your net income after it. The CRA arrives at Line 23600 by taking Line 15000 and subtracting everything through Line 23500.1Canada Revenue Agency. Line 23600 – Net Income
For most people the two numbers are identical. If you don’t owe an OAS or EI repayment, Line 23500 is zero and Lines 23400 and 23600 match. The gap only opens up when your income is high enough to trigger a clawback, which is exactly the situation where knowing which line a program uses starts to matter.
Why Line 23400 Matters for OAS and EI Repayment
The Old Age Security pension recovery tax is the main reason Line 23400 exists as its own line. The CRA looks at your net income before adjustments to decide whether you must repay part or all of your OAS pension. For the 2026 tax year, the threshold is $95,323. If your Line 23400 exceeds that amount, you owe 15% of every dollar above the threshold.8Government of Canada. Old Age Security Pension Recovery Tax
The repayment keeps climbing until your OAS pension is fully clawed back. For 2026, that point is $154,753 for recipients aged 65 to 74 and $160,696 for those 75 and older.8Government of Canada. Old Age Security Pension Recovery Tax The repayment amount goes on Line 23500 and is then subtracted to produce your final net income on Line 23600.9Canada.ca. Line 23500 – Social Benefits Repayment
Employment Insurance benefits work the same way. For the 2025 tax year, you must repay part of your EI benefits if your net income after specific adjustments exceeds $82,125.9Canada.ca. Line 23500 – Social Benefits Repayment The calculation starts from Line 23400, with adjustments for items like UCCB and RDSP amounts.
Benefits That Use Line 23600 Instead
If you assume Line 23400 drives every benefit program, you’ll be off. Most federal benefits actually look at Line 23600, your final net income.
The Canada Child Benefit builds your adjusted family net income from Line 23600 of your return and your spouse’s or common-law partner’s return, then reduces the benefit as that combined figure rises.10Canada.ca. How Much You Can Get – Canada Child Benefit The GST/HST credit works the same way and phases out as income climbs.11Canada.ca. How Your GST/HST Credit Is Calculated The Canada Workers Benefit also starts from Line 23600.
There is a practical upside here. Any deduction that reduces your Line 23400, whether an RRSP contribution, child care expense, or support payment, also lowers your Line 23600. The same dollar can shrink an OAS clawback and lift a Canada Child Benefit payment at the same time.
Keep Your Documentation
Every deduction feeding into Line 23400 needs supporting records you can produce if the CRA asks. Keep your tax records for at least six years from the end of the tax year they relate to, even if you filed electronically and didn’t attach anything to the return.12Canada Revenue Agency. How Long Should You Keep Your Income Tax Records The CRA may want more than receipts, including cancelled cheques and bank statements. If you claimed employment expenses, hold onto the signed T2200 from your employer and your Form T777 for the full six years.7Canada Revenue Agency. Employment Expenses 2025 Missing paperwork during a review can mean denied deductions, a reassessment, and interest on any additional tax owing.