How we know the numbers are right

The suite runs on every change with npm run verify, alongside a full TypeScript check and a production build. A failing assertion blocks the build, so a wrong figure cannot reach the site by accident.

• Contribution maximums

  Every published CPP, CPP2, EI, Quebec EI, QPP, QPP2 and QPIP employee maximum, asserted to the cent at the ceiling and one dollar either side of it.

• Ontario Health Premium bands

  All 16 band boundaries, tested at the boundary and at one dollar on each side, because a band applied one dollar early overcharges a whole income range.

• Monotonicity

  Net pay must never fall as gross pay rises, from $10,000 to $400,000 of income, in all 13 jurisdictions. A single non-monotonic point means a bracket or a phase-out is wired wrong.

• Frequency invariance

  The same annual salary must produce the same annual deductions whether it is paid weekly, bi-weekly, semi-monthly or monthly.

• Deduction reconciliation

  Gross minus every deduction must equal net, exactly, at every tested income.

• Quebec-specific structure

  The 16.5% federal abatement, the QPP and QPIP substitution for CPP and EI, and the lower Quebec EI rate.

These are real defects that were live on this site and are now fixed. They are published because a page claiming accuracy without showing its failures is worth nothing.

• The whole CPP contribution was being credited at the lowest tax rate. Only the 4.95% base slice is a credit — the 1% enhanced slice and all of CPP2 are a deduction from income. Both legs were wrong.
• The provincial credit for CPP and EI (T4127 factor K2P) was missing entirely, so provincial tax was overstated in all 13 jurisdictions.
• The Canada Employment Amount was missing, overstating federal tax by up to $210.14 a year for every employee in the country.
• The Quebec federal abatement was missing, overstating federal tax by 16.5% for every Quebec user.
• The Ontario surtax thresholds were $6,000 and $7,800. The 2026 figures are $5,818 and $7,446.
• Alberta was charging 10% from the first dollar. The rate is 8% to $61,200, then 10, 12, 13, 14 and 15%.
• The Quebec EI rate was 1.25% with an $861.25 maximum. The 2026 figures are 1.30% and $895.70.
• The Ontario Health Premium band caps were wrong, overcharging by up to $3,500 across the $48,000–$72,000 income range.

Together those defects understated take-home pay for an Ontario employee on $62,000 by $519.62 a year. In Quebec the error was larger.

Minimum wage, overtime, vacation, public holidays and final-pay deadlines for all 13 jurisdictions were read from each government’s own page on 27 August 2026 and then re-checked by a second, independent pass instructed to refute the first. All 13 agreed. The one defect found was a New Brunswick source URL that had moved, which has been repointed.

Minimum wage is stored as a dated schedule rather than a single number, so a rate that is already published takes effect on its own date instead of waiting for an editor to notice. Both the rate in force and the scheduled one are shown with their dates.

The engine models the annual legislated rates. It does not model the mid-year prorated withholding rates British Columbia and Prince Edward Island use from July 2026, and it does not model TD1 claims beyond the basic personal amount. Both limits are stated in the calculator’s own “what this includes” block.

It is a check, not a payroll system. Your employer’s figures can differ legitimately — a mid-year start, a taxable benefit, a second job, a TD1 with extra claims, or a pension adjustment will all move the numbers. Use it to find the question worth asking, not to prove someone wrong.

If you find a figure that is wrong, say so and it gets fixed the same week and the correction is recorded. Email hello@paystubiq.com. The raw data is published at open payroll data so a disagreement can be settled by looking at the same numbers.