Ontario provincial income tax for a self-employed sole proprietor.
Written by the OpenAccountants team. Written by the OpenAccountants team from the official sources it cites.
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Ontario Surtax
20% on basic tax exceeding $5,315 + 36% on basic tax exceeding $6,802. Thresholds NOT indexed.
Required Inputs
Minimum viable -- province of residence on Dec 31 (must be Ontario), federal taxable income (T1 line 26000), federal net income. Recommended -- marital status, spouse income, children, property tax/rent paid, municipality. Ideal -- complete T1 data, prior ON428, disability certificate.
R-ON-1 -- Not Ontario resident
"Province is not Ontario on December 31."
R-ON-2 -- Corporations/trusts
"Individual sole proprietors only."
R-ON-3 -- Part-year resident
"Escalate."
R-ON-4 -- First Nations exemption
"Escalate."
Ontario Tax Computation
Taxable income -> 5 brackets -> gross tax -> minus non-refundable credits at 5.05% -> basic tax -> plus surtax -> plus OHP.
Ontario Surtax formula
Surtax = 20% x max(0, basic_tax - $5,315) + 36% x max(0, basic_tax - $6,802). Thresholds frozen (not indexed).
OHP basis
Based on taxable income (not net income). Maximum $900. NOT reduced by credits.
Basic personal credit
$11,865
Spousal credit
$11,865 minus partner income
Age (65+) credit
$5,590
Ontario Trillium Benefit
OEPTC: max $1,194 (non-senior). OSTC: $360/person. NOEC: $180 (Northern Ontario only). All reduced by income. Paid by CRA. Flag for reviewer.
CARE Credit
Refundable childcare credit, percentage depends on family income. Flag if client has childcare expenses.
Multiple Provinces
If multi-province allocation required (T2203), flag for reviewer.
Rendered from the canonical facts model. General reference only — confirm with a qualified professional before acting.
Quick Reference
| Field | Value |
|---|---|
| Country | Canada -- Ontario |
| Tax | Provincial income tax (ON428) + Ontario Health Premium + Ontario surtax |
| Currency | CAD only |
| Tax year | Calendar year |
| Primary legislation | Taxation Act, 2007, S.O. 2007, c. 11, Sch. A |
| Tax authority | CRA on behalf of Ontario |
| Filing portal | CRA My Account / NETFILE / EFILE |
| Form | ON428 -- Ontario Tax; ON479 (Credits); ON-BEN (Trillium) |
| Filing deadline | June 15 (self-employed); payment due April 30 |
| Contributor | Open Accountants Community |
| Validated by | Live status: https://openaccountants.com/skills/on-individual-return |
| Skill version | 2.0 |
Ontario Tax Rates (2025)
| Taxable Income (CAD) | Rate | Cumulative Tax |
|---|---|---|
| 0 -- 52,886 | 5.05% | 2,671 |
| 52,887 -- 105,775 | 9.15% | 7,510 |
| 105,776 -- 150,000 | 11.16% | 12,447 |
| 150,001 -- 220,000 | 12.16% | 20,959 |
| 220,001+ | 13.16% | 20,959+ |
Ontario Health Premium (OHP)
| Taxable Income | OHP |
|---|---|
| 0 -- 20,000 | $0 |
| 20,001 -- 25,000 | 6% of excess over $20,000 (max $300) |
| 25,001 -- 36,000 | $300 |
| 36,001 -- 48,000 | Step increases to $600 |
| 48,601 -- 72,000 | $600 |
| 72,601 -- 200,000 | $750 |
| 200,601+ | $900 (maximum) |
Conservative Defaults
| Ambiguity | Default |
|---|---|
| Unknown province | Do not apply this skill |
| Unknown bracket year | 2025 indexed figures |
Ontario tax is computed from federal return data. Transaction classification is in ca-fed-t2125.
Input: Taxable income $18,000. Single.
Computation:
Input: Taxable income $75,000. Single.
Computation:
Input: Taxable income $200,000. Single.
Computation:
ONTARIO PROVINCIAL TAX -- Working Paper (2025)
A. INCOME A1. Taxable income (T1 line 26000) ___________
B. ONTARIO TAX B1. Gross Ontario tax (5 brackets) ___________ B2. Ontario non-refundable credits (x 5.05%) ___________ B3. Ontario basic tax (B1 - B2, min 0) ___________ B4. Ontario surtax ___________ B5. Ontario tax before OHP (B3 + B4) ___________ B6. Ontario Health Premium ___________ B7. Ontario tax payable (B5 + B6) ___________
REVIEWER FLAGS: [ ] Province confirmed as Ontario? [ ] Surtax computed on basic tax (after credits)? [ ] OHP NOT reduced by credits? [ ] 2025 indexed thresholds used?
Ontario tax is not computed from bank statements directly. See ca-fed-t2125.
ONBOARDING QUESTIONS -- ONTARIO PROVINCIAL TAX
Reference Material
| Topic | Reference |
|---|---|
| Ontario brackets | Taxation Act, 2007, s. 3 |
| Surtax | Taxation Act, 2007, s. 3(2) |
| OHP | Taxation Act, 2007, s. 3(5) |
| Non-refundable credits | Taxation Act, 2007, s. 8+ |
| OTB / OEPTC | Taxation Act, 2007, Part IV |
| Dividend tax credits | Taxation Act, 2007, s. 19 |
This skill and its outputs are provided for informational and computational purposes only and do not constitute tax, legal, or financial advice. Open Accountants and its contributors accept no liability for any errors, omissions, or outcomes arising from the use of this skill. All outputs must be reviewed and signed off by a qualified professional before filing or acting upon.
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Other Canada computations in the OpenAccountants Tax Library.
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