Ontario Provincial Income Tax -- Sole Proprietor Skill v2.0
General reference only. This skill is general tax/accounting reference material for AI-assisted workflows. It has not been reviewed for any specific person's facts, documents, elections, deadlines, residency, filing status, or local procedures. Do not rely on it to file, pay, amend, or take a tax position without review by a qualified professional in the relevant jurisdiction.
Section 1 -- 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 |
Pending -- Canadian CPA sign-off required |
| 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 Surtax
20% on basic tax exceeding $5,315 + 36% on basic tax exceeding $6,802. Thresholds NOT indexed.
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 |
Section 2 -- Required Inputs and Refusal Catalogue
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.
Refusal Catalogue
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."
Section 3 -- Transaction Pattern Library
Ontario tax is computed from federal return data. Transaction classification is in ca-fed-t2125.
Section 4 -- Worked Examples
Example 1 -- Low Income
Input: Taxable income $18,000. Single.
Computation:
- Gross Ontario tax: $18,000 x 5.05% = $909.00
- Basic personal credit: $11,865 x 5.05% = $599.18
- Basic tax: $309.82. Surtax: $0. OHP: $0.
- Ontario tax: $309.82
Example 2 -- Mid-Range
Input: Taxable income $75,000. Single.
Computation:
- $52,886 at 5.05% + $22,114 at 9.15% = $4,694.17
- Credit: $599.18. Basic tax: $4,094.99. Surtax: $0. OHP: $750.
- Ontario tax: $4,844.99
Example 3 -- High Income, Surtax
Input: Taxable income $200,000. Single.
Computation:
- Gross tax through brackets: $18,525.59
- Credit: $599.18. Basic tax: $17,926.41
- Surtax 1: 20% x ($17,926.41 - $5,315) = $2,522.28
- Surtax 2: 36% x ($17,926.41 - $6,802) = $4,004.79
- OHP: $750
- Ontario tax: $17,926.41 + $6,527.07 + $750 = $25,203.48
Section 5 -- Tier 1 Rules (When Data Is Clear)
5.1 Ontario Tax Computation
Taxable income -> 5 brackets -> gross tax -> minus non-refundable credits at 5.05% -> basic tax -> plus surtax -> plus OHP.
5.2 Ontario Surtax
Surtax = 20% x max(0, basic_tax - $5,315) + 36% x max(0, basic_tax - $6,802). Thresholds frozen (not indexed).
5.3 OHP
Based on taxable income (not net income). Maximum $900. NOT reduced by credits.
5.4 Credits at 5.05%
Basic personal: $11,865. Spousal: $11,865 minus partner income. Age (65+): $5,590.
Section 6 -- Tier 2 Catalogue (Reviewer Judgement Required)
6.1 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.
6.2 CARE Credit
Refundable childcare credit, percentage depends on family income. Flag if client has childcare expenses.
6.3 Multiple Provinces
If multi-province allocation required (T2203), flag for reviewer.
Section 7 -- Excel Working Paper Template
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?
Section 8 -- Bank Statement Reading Guide
Ontario tax is not computed from bank statements directly. See ca-fed-t2125.
Section 9 -- Onboarding Fallback
ONBOARDING QUESTIONS -- ONTARIO PROVINCIAL TAX
1. Province of residence on December 31?
2. Federal taxable income?
3. Federal net income?
4. Marital status and spouse income?
5. Number of children?
6. Property tax or rent paid?
7. Northern Ontario resident?
8. Medical expenses, charitable donations?
9. Disability status?
10. Childcare expenses?
Section 10 -- 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 |
PROHIBITIONS
- NEVER apply this skill if province is not Ontario on December 31
- NEVER reduce the OHP by tax credits
- NEVER forget the surtax -- it dramatically increases effective rates
- NEVER compute tax for corporations, partnerships, or trusts
- NEVER use prior-year bracket amounts
- NEVER combine with another provincial skill
- NEVER present calculations as definitive
Disclaimer
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.
The most up-to-date, verified version of this skill is maintained at openaccountants.com.
Source: OpenAccountants — open tax Guides for AI, reviewed by named CPAs/CAs/EAs. Quality: source-cited draft. For always-current figures and named-accountant backing, connect the OpenAccountants MCP server (openaccountants-mcp).
1---2name: on-individual-return3description: > Use this skill whenever asked about Ontario provincial income tax for a self-employed sole proprietor. Trigger on phrases like "Ontario tax", "ON428", "Ontario income tax", "Ontario surtax", "Ontario Health Premium", "OHP", "OEPTC", "Ontario trillium", "provincial tax Ontario", or any question about computing Ontario provincial tax. ALWAYS read this skill before touching any Ontario provincial tax work.4license: AGPL-3.0-or-later (code) / OpenAccountants Guide License v1.0 (c5---67# Ontario Provincial Income Tax -- Sole Proprietor Skill v2.089> **General reference only.** This skill is general tax/accounting reference material for AI-assisted workflows. It has not been reviewed for any specific person's facts, documents, elections, deadlines, residency, filing status, or local procedures. Do not rely on it to file, pay, amend, or take a tax position without review by a qualified professional in the relevant jurisdiction.1011---1213## Section 1 -- Quick Reference1415| Field | Value |16|---|---|17| Country | Canada -- Ontario |18| Tax | Provincial income tax (ON428) + Ontario Health Premium + Ontario surtax |19| Currency | CAD only |20| Tax year | Calendar year |21| Primary legislation | Taxation Act, 2007, S.O. 2007, c. 11, Sch. A |22| Tax authority | CRA on behalf of Ontario |23| Filing portal | CRA My Account / NETFILE / EFILE |24| Form | ON428 -- Ontario Tax; ON479 (Credits); ON-BEN (Trillium) |25| Filing deadline | June 15 (self-employed); payment due April 30 |26| Contributor | Open Accountants Community |27| Validated by | Pending -- Canadian CPA sign-off required |28| Skill version | 2.0 |2930### Ontario Tax Rates (2025)3132| Taxable Income (CAD) | Rate | Cumulative Tax |33|---|---|---|34| 0 -- 52,886 | 5.05% | 2,671 |35| 52,887 -- 105,775 | 9.15% | 7,510 |36| 105,776 -- 150,000 | 11.16% | 12,447 |37| 150,001 -- 220,000 | 12.16% | 20,959 |38| 220,001+ | 13.16% | 20,959+ |3940### Ontario Surtax414220% on basic tax exceeding $5,315 + 36% on basic tax exceeding $6,802. Thresholds NOT indexed.4344### Ontario Health Premium (OHP)4546| Taxable Income | OHP |47|---|---|48| 0 -- 20,000 | $0 |49| 20,001 -- 25,000 | 6% of excess over $20,000 (max $300) |50| 25,001 -- 36,000 | $300 |51| 36,001 -- 48,000 | Step increases to $600 |52| 48,601 -- 72,000 | $600 |53| 72,601 -- 200,000 | $750 |54| 200,601+ | $900 (maximum) |5556### Conservative Defaults5758| Ambiguity | Default |59|---|---|60| Unknown province | Do not apply this skill |61| Unknown bracket year | 2025 indexed figures |6263---6465## Section 2 -- Required Inputs and Refusal Catalogue6667### Required Inputs6869**Minimum viable** -- province of residence on Dec 31 (must be Ontario), federal taxable income (T1 line 26000), federal net income.7071**Recommended** -- marital status, spouse income, children, property tax/rent paid, municipality.7273**Ideal** -- complete T1 data, prior ON428, disability certificate.7475### Refusal Catalogue7677**R-ON-1 -- Not Ontario resident.** "Province is not Ontario on December 31."7879**R-ON-2 -- Corporations/trusts.** "Individual sole proprietors only."8081**R-ON-3 -- Part-year resident.** "Escalate."8283**R-ON-4 -- First Nations exemption.** "Escalate."8485---8687## Section 3 -- Transaction Pattern Library8889Ontario tax is computed from federal return data. Transaction classification is in `ca-fed-t2125`.9091---9293## Section 4 -- Worked Examples9495### Example 1 -- Low Income9697**Input:** Taxable income $18,000. Single.9899**Computation:**100- Gross Ontario tax: $18,000 x 5.05% = $909.00101- Basic personal credit: $11,865 x 5.05% = $599.18102- Basic tax: $309.82. Surtax: $0. OHP: $0.103- Ontario tax: $309.82104105### Example 2 -- Mid-Range106107**Input:** Taxable income $75,000. Single.108109**Computation:**110- $52,886 at 5.05% + $22,114 at 9.15% = $4,694.17111- Credit: $599.18. Basic tax: $4,094.99. Surtax: $0. OHP: $750.112- Ontario tax: $4,844.99113114### Example 3 -- High Income, Surtax115116**Input:** Taxable income $200,000. Single.117118**Computation:**119- Gross tax through brackets: $18,525.59120- Credit: $599.18. Basic tax: $17,926.41121- Surtax 1: 20% x ($17,926.41 - $5,315) = $2,522.28122- Surtax 2: 36% x ($17,926.41 - $6,802) = $4,004.79123- OHP: $750124- Ontario tax: $17,926.41 + $6,527.07 + $750 = $25,203.48125126---127128## Section 5 -- Tier 1 Rules (When Data Is Clear)129130### 5.1 Ontario Tax Computation131132Taxable income -> 5 brackets -> gross tax -> minus non-refundable credits at 5.05% -> basic tax -> plus surtax -> plus OHP.133134### 5.2 Ontario Surtax135136Surtax = 20% x max(0, basic_tax - $5,315) + 36% x max(0, basic_tax - $6,802). Thresholds frozen (not indexed).137138### 5.3 OHP139140Based on taxable income (not net income). Maximum $900. NOT reduced by credits.141142### 5.4 Credits at 5.05%143144Basic personal: $11,865. Spousal: $11,865 minus partner income. Age (65+): $5,590.145146---147148## Section 6 -- Tier 2 Catalogue (Reviewer Judgement Required)149150### 6.1 Ontario Trillium Benefit151152OEPTC: max $1,194 (non-senior). OSTC: $360/person. NOEC: $180 (Northern Ontario only). All reduced by income. Paid by CRA. Flag for reviewer.153154### 6.2 CARE Credit155156Refundable childcare credit, percentage depends on family income. Flag if client has childcare expenses.157158### 6.3 Multiple Provinces159160If multi-province allocation required (T2203), flag for reviewer.161162---163164## Section 7 -- Excel Working Paper Template165166```167ONTARIO PROVINCIAL TAX -- Working Paper (2025)168169A. INCOME170 A1. Taxable income (T1 line 26000) ___________171172B. ONTARIO TAX173 B1. Gross Ontario tax (5 brackets) ___________174 B2. Ontario non-refundable credits (x 5.05%) ___________175 B3. Ontario basic tax (B1 - B2, min 0) ___________176 B4. Ontario surtax ___________177 B5. Ontario tax before OHP (B3 + B4) ___________178 B6. Ontario Health Premium ___________179 B7. Ontario tax payable (B5 + B6) ___________180181REVIEWER FLAGS:182 [ ] Province confirmed as Ontario?183 [ ] Surtax computed on basic tax (after credits)?184 [ ] OHP NOT reduced by credits?185 [ ] 2025 indexed thresholds used?186```187188---189190## Section 8 -- Bank Statement Reading Guide191192Ontario tax is not computed from bank statements directly. See `ca-fed-t2125`.193194---195196## Section 9 -- Onboarding Fallback197198```199ONBOARDING QUESTIONS -- ONTARIO PROVINCIAL TAX2001. Province of residence on December 31?2012. Federal taxable income?2023. Federal net income?2034. Marital status and spouse income?2045. Number of children?2056. Property tax or rent paid?2067. Northern Ontario resident?2078. Medical expenses, charitable donations?2089. Disability status?20910. Childcare expenses?210```211212---213214## Section 10 -- Reference Material215216| Topic | Reference |217|---|---|218| Ontario brackets | Taxation Act, 2007, s. 3 |219| Surtax | Taxation Act, 2007, s. 3(2) |220| OHP | Taxation Act, 2007, s. 3(5) |221| Non-refundable credits | Taxation Act, 2007, s. 8+ |222| OTB / OEPTC | Taxation Act, 2007, Part IV |223| Dividend tax credits | Taxation Act, 2007, s. 19 |224225---226227## PROHIBITIONS228229- NEVER apply this skill if province is not Ontario on December 31230- NEVER reduce the OHP by tax credits231- NEVER forget the surtax -- it dramatically increases effective rates232- NEVER compute tax for corporations, partnerships, or trusts233- NEVER use prior-year bracket amounts234- NEVER combine with another provincial skill235- NEVER present calculations as definitive236237---238239## Disclaimer240241This 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.242243The most up-to-date, verified version of this skill is maintained at [openaccountants.com](https://openaccountants.com).244245---246247_Source: [OpenAccountants](https://openaccountants.com/skills/on-individual-return) — open tax Guides for AI, reviewed by named CPAs/CAs/EAs. Quality: **source-cited draft**. For always-current figures and named-accountant backing, connect the OpenAccountants MCP server (`openaccountants-mcp`)._
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