Key Takeaways
- 1.The federal SBD grind starts at $50,000 AAII and eliminates the deduction entirely at $150,000 AAII. Each $1 above $50K reduces the $500,000 SBD limit by $5.
- 2.A $500,000 corporate portfolio earning 10% in interest generates $50,000 in AAII — right at the threshold. A single dollar more triggers the grind.
- 3.Ontario did not adopt the federal AAII-based SBD grind for provincial tax. An Ontario CCPC with $160K AAII still pays the 3.2% provincial small business rate — yielding a combined rate of ~18.2% vs. ~26.5% in BC.
- 4.Passive investment income inside a CCPC is taxed at ~50.17% in Ontario, but 30.67% is refundable through RDTOH when taxable dividends are paid out.
- 5.Salary extraction before corporate savings accumulate, permanent life insurance, and Canadian dividend ETFs (whose dividends are excluded from AAII) are the primary strategies to stay below the $50,000 threshold.
The SBD Grind Mechanics: $5 Reduction for Every $1 of Passive Income
The small business deduction (SBD) allows CCPCs to pay a reduced federal tax rate of 9% (instead of 15%) on the first $500,000 of active business income. Since 2019, the federal government has clawed back this deduction based on the corporation's prior-year adjusted aggregate investment income (AAII).
Federal SBD grind formula:
Business limit reduction = (AAII − $50,000) × $5
AAII = $50,000 → Reduction = $0 (full $500K SBD available)
AAII = $75,000 → Reduction = ($75,000 − $50,000) × $5 = $125,000
Remaining SBD: $500,000 − $125,000 = $375,000
AAII = $100,000 → Reduction = $250,000 → Remaining SBD: $250,000
AAII = $150,000 → Reduction = $500,000 → Remaining SBD: $0
The grind is aggressive by design: at a 5:1 ratio, the full $500,000 deduction disappears over a $100,000 range of passive income ($50K to $150K). A CCPC earning $500,000 of active business income and $150,000 of passive investment income pays the 15% federal general rate on all active income — costing an additional $30,000 in federal tax compared to the 9% small business rate. For context on how salary vs. dividend decisions interact with corporate tax planning, see our salary vs. dividend calculator for Ontario small business owners.
What Counts as AAII: The Income Types That Trigger the Grind
Not all corporate investment income contributes equally to AAII. Understanding which income types count is essential for staying below the $50,000 threshold.
| Income Type | Included in AAII? | Notes |
|---|---|---|
| Interest (GICs, bonds, savings) | Yes — 100% | Full amount counts toward AAII |
| Taxable capital gains | Yes — taxable portion | 2/3 inclusion rate since June 2024 for corps |
| Rental income (net) | Yes — 100% | Net of expenses; passive rental only |
| Eligible dividends from public corps | No | Taxed under Part IV; excluded from AAII |
| Active business income | No | SBD applies to this income |
| Life insurance CSV growth | No | Exempt until policy disposition |
AAII is based on the prior tax year. A spike in realized capital gains in 2025 triggers the grind in the 2026 tax year. Eligible dividends from connected private corporations may or may not be included depending on whether Part IV tax applies.
Refundable Tax and RDTOH: The 50.17% Rate That Isn't Permanent
When a CCPC earns passive investment income in Ontario, the combined federal-provincial corporate tax rate is approximately 50.17%. This is deliberately high — higher than the top personal marginal rate in Ontario (53.53%) — to discourage indefinite tax deferral inside the corporation.
However, a significant portion of this tax is refundable. The federal refundable tax of 30.67% is added to the corporation's RDTOH (Refundable Dividend Tax on Hand) account. When the corporation pays taxable dividends to shareholders, it receives a dividend refund from the RDTOH balance.
RDTOH and dividend refund mechanics (Ontario CCPC):
Corporate investment income earned: $100,000
Combined tax at ~50.17%: $50,170
Breakdown:
• Non-refundable federal + provincial tax: ~$19,500
• Refundable tax added to RDTOH: ~$30,670
When the corporation pays $80,000 in taxable dividends:
Dividend refund = lesser of RDTOH balance or 38.33% of dividends paid
= 38.33% × $80,000 = $30,664 refunded
Net corporate tax retained: ~$19,500 (effective rate: ~19.5%)
The shareholder then pays personal tax on the $80,000 dividend.
The RDTOH mechanism ensures that corporate investment income is not permanently double-taxed. But the refund only flows when dividends are paid — if you retain investment income inside the corporation indefinitely, the full ~50% rate applies until distribution. For a deeper look at how professional corporations manage the salary-dividend split, see our professional corporation salary vs. dividend calculator.
Worked Example: $500K Portfolio at 10% Return Inside an Ontario CCPC
Our Ontario small business owner has $500,000 of active business income and a corporate investment portfolio of $500,000. We compare two scenarios: the portfolio held entirely in GICs earning 5% interest, and the portfolio held in a Canadian equity ETF earning 3% eligible dividends plus 5% in unrealized capital gains (2% realized annually).
| Line Item | GIC Portfolio (5% interest) | Equity ETF (3% div + 2% gains) |
|---|---|---|
| Annual investment income | $25,000 interest | $15,000 div + $10,000 gains |
| AAII contribution | $25,000 | $6,667 (gains only) |
| SBD grind triggered? | No (under $50K) | No (under $50K) |
| Corporate tax on investment income | ~$12,543 | ~$8,850 |
| Federal tax on $500K active income | 9% = $45,000 | 9% = $45,000 |
At these income levels, neither portfolio triggers the SBD grind. But double the GIC portfolio to $1M and the $50,000 interest pushes AAII to the threshold.
Now consider a larger portfolio — $1,000,000 in GICs earning $50,000 in interest. That hits the AAII threshold exactly. One more dollar of interest and the grind begins. At $1,500,000 in GICs earning $75,000, the SBD limit drops to $375,000, and $125,000 of active business income is taxed at 15% instead of 9% — costing an additional $7,500 in federal tax.
The Ontario Advantage: Why the Provincial SBD Survives the Federal Grind
This is the gap that most calculators and articles miss entirely. When the federal government introduced the AAII-based SBD grind in 2019, each province could choose whether to apply the same grind to their provincial small business deduction. Ontario chose not to. Neither did New Brunswick.
The practical consequence: an Ontario CCPC that has its federal SBD fully ground to zero (because AAII exceeds $150,000) still pays the Ontario small business rate of 3.2% on the first $500,000 of active business income — not the Ontario general rate of 11.5%. In BC and Alberta, the provincial SBD grinds in lockstep with the federal SBD.
| Province | Federal Rate | Provincial Rate | Combined Rate | Tax on $500K ABI |
|---|---|---|---|---|
| Ontario (no prov. grind) | 15.0% | 3.2% | 18.2% | $91,000 |
| BC (prov. grind applies) | 15.0% | 12.0% | 27.0% | $135,000 |
| Alberta (prov. grind applies) | 15.0% | 8.0% | 23.0% | $115,000 |
| Ontario advantage vs. BC | $44,000 saved | |||
| Ontario advantage vs. Alberta | $24,000 saved | |||
Scenario: CCPC with $500,000 active business income and AAII > $150,000 (federal SBD fully ground). Federal rate is the general 15% in all provinces. Provincial rates reflect whether the province applies its own SBD grind. Figures are for the 2026 tax year using current enacted rates.
This is a $44,000 annual advantage for an Ontario CCPC over an identical BC corporation — purely because Ontario preserved its provincial small business rate for corporations that exceed the federal passive income threshold. For an incorporated professional earning $500,000 in active income with substantial corporate investments, this Ontario exemption is worth more than many tax planning strategies.
The Full Picture: Tax on $500K Active Income + $160K Passive Income in Ontario
Let us put together the complete 2026 tax picture for an Ontario CCPC earning $500,000 in active business income and $160,000 in passive investment income (all interest), with the owner taking a $150,000 salary. For more on the trade-offs of salary extraction in a small business, see our Ontario small business sale tax calculator.
Active business income tax (Ontario CCPC, AAII > $150K):
Active business income: $500,000
Less: salary paid to owner: −$150,000
Net active income in corp: $350,000
Federal SBD available: $0 (AAII of $160K exceeds $150K threshold)
Federal tax: $350,000 × 15% = $52,500
Ontario provincial tax: $350,000 × 3.2% = $11,200
(Ontario SBD still available — no provincial grind)
Total tax on active income: $63,700 (effective rate: 18.2%)
If Ontario also applied the grind:
Ontario tax would be: $350,000 × 11.5% = $40,250
Total would be: $92,750 (effective rate: 26.5%)
Ontario exemption saves: $29,050
Passive investment income tax (Ontario CCPC):
Passive investment income (interest): $160,000
Combined tax at ~50.17%: $80,272
Refundable portion (RDTOH): $160,000 × 30.67% = $49,072
Non-refundable portion: $80,272 − $49,072 = $31,200
When dividends are paid to recover RDTOH:
Dividend refund rate: 38.33% of dividends paid
Dividends needed to recover full RDTOH: $49,072 ÷ 0.3833 = ~$128,000
Net corporate tax on investment income after refund: ~$31,200 (19.5%)
Shareholder then pays personal tax on the $128,000 in dividends received.
Salary Extraction Strategy: Keeping AAII Below $50,000
The most straightforward way to avoid the SBD grind is to prevent corporate retained earnings from accumulating into a portfolio large enough to generate $50,000 in AAII. This means extracting more income as salary or dividends each year rather than leaving it inside the corporation.
Maximum portfolio size to stay under $50K AAII (by asset class):
GICs at 5% interest:
$50,000 ÷ 5% = $1,000,000 maximum portfolio
Balanced portfolio (2% interest + 3% realized capital gains):
AAII = $20,000 interest + $20,000 taxable gains (2/3 of $30K) = $40,000
Portfolio size: $1,000,000 (still under threshold)
Canadian dividend ETF (4% eligible dividends + 1% realized gains):
AAII = $0 dividends + $6,667 taxable gains (2/3 of $10K) = $6,667
Portfolio size: $1,000,000 (well under threshold)
Key insight: The same $1M portfolio can generate $6,667 or $50,000 in AAII depending on asset mix. Canadian dividend ETFs are the most AAII-efficient, while GICs are the least.
For business owners who want to retain more inside the corporation, the salary extraction calculus changes. Paying an additional $50,000 in salary (at a ~43% personal marginal rate in Ontario) costs approximately $21,500 in personal income tax — but it prevents $50,000 from being invested inside the corp, which prevents up to $2,500 in annual AAII (at 5% interest), which prevents up to $12,500 in SBD grind. The break-even depends on time horizon and expected returns. For self-employed business owners managing quarterly installments on this salary, see our CRA quarterly tax instalment calculator.
GICs vs. Equity ETFs: After-Tax Comparison Inside the Corp
The choice between interest-bearing investments and equity investments inside a CCPC involves two layers of tax consequence: the corporate-level tax on investment income, and the SBD grind caused by AAII. Here is a side-by-side comparison for $500,000 invested.
| Metric | $500K in GICs (5%) | $500K Cdn Div ETF (4% + 2%) |
|---|---|---|
| Gross annual return | $25,000 | $30,000 |
| AAII contribution | $25,000 | $6,667 |
| Corporate tax (before RDTOH refund) | $12,543 | $10,950 |
| RDTOH recoverable on dividends | $7,668 | $7,666 |
| Net corp tax after RDTOH refund | $4,875 | $3,284 |
| SBD grind (if $400K ABI also present) | $0 (under $50K) | $0 (under $50K) |
| After-corp-tax retention | $20,125 | $26,716 |
The equity ETF assumes 4% in eligible Canadian dividends (Part IV tax, fully refundable via ERDTOH) and 2% in realized capital gains (2/3 inclusion). The GIC assumes 5% interest. Both scenarios assume $500,000 investment balance and an Ontario CCPC. Personal tax on dividend extraction is not shown. Figures are approximate.
Four Mitigation Strategies for the SBD Grind
If your corporate portfolio is already large enough to generate significant AAII, or is on track to reach that level, these are the primary strategies to mitigate or avoid the grind.
1. Pay out retained earnings before they accumulate
Extract more salary or dividends each year so less capital sits inside the corp. The personal tax cost of extraction must be weighed against the SBD grind cost of retaining the funds. At a 43% personal marginal rate, extracting $100,000 costs $43,000 in personal tax — but prevents $5,000 in annual AAII (at 5%), which prevents up to $25,000 in SBD grind.
2. Use permanent life insurance inside the corporation
The cash surrender value growth inside a permanent life insurance policy is not included in AII/AAII. The capital death benefit passes to the corporation tax-free through the capital dividend account. This is the most common strategy for CCPC owners with large retained earnings and no immediate need for the funds.
3. Shift from interest to eligible Canadian dividends
Eligible dividends from public Canadian corporations are excluded from AAII. A portfolio of Canadian dividend-paying ETFs generates investment return without contributing to the SBD grind (capital gains on disposition still count at the taxable portion).
4. Individual Pension Plan (IPP) for owner-managers over 40
An IPP is a defined benefit pension plan for one or a few members. Contributions are deductible to the corporation and remove assets from the corporate environment entirely, reducing both the investment portfolio and future AAII. For owner-managers over 50, IPP contribution room often exceeds RRSP room significantly.
For owner-managers evaluating CPP contributions as part of their total compensation strategy, see our small business owner CPP contributions calculator.
The Capital Gains Inclusion Rate Change: 2/3 Since June 2024
The June 2024 increase in the capital gains inclusion rate from 1/2 to 2/3 for corporations (and for individuals above $250,000 in annual gains) amplifies the SBD grind problem. A $150,000 capital gain inside a CCPC now generates $100,000 in taxable capital gain (and therefore $100,000 in AAII), compared to $75,000 under the old 1/2 rate. This means the same portfolio of equity investments produces 33% more AAII per dollar of capital gain realized — pushing more CCPCs over the $50,000 threshold.
Impact of 2/3 inclusion on SBD grind (example):
Realized capital gain: $120,000
Under 1/2 inclusion (pre-June 2024):
Taxable capital gain (AAII): $60,000
SBD grind: ($60,000 − $50,000) × $5 = $50,000 reduction
Remaining SBD: $450,000
Under 2/3 inclusion (current):
Taxable capital gain (AAII): $80,000
SBD grind: ($80,000 − $50,000) × $5 = $150,000 reduction
Remaining SBD: $350,000
Additional SBD lost due to rate change: $100,000
Additional tax cost (at 6% federal rate differential): $6,000
Important Disclaimer
This article provides general information about the federal small business deduction grind, refundable taxes (RDTOH), and Ontario's provincial SBD exemption from the AAII-based grind. It is not legal, financial, or tax advice. The federal small business tax rate of 9%, the general rate of 15%, the Ontario small business rate of 3.2%, and the Ontario general rate of 11.5% are based on enacted rates for the 2026 tax year. The $50,000 AAII threshold and $5-for-$1 grind formula are set out in subsection 125(5.1) of the Income Tax Act. Ontario's non-adoption of the AAII-based grind is reflected in Ontario's Taxation Act, 2007. The 2/3 capital gains inclusion rate for corporations applies to dispositions after June 24, 2024. Provincial rates and grind rules in BC, Alberta, and other provinces are as enacted for 2026 and may change. RDTOH recovery rates and dividend refund calculations are simplified; actual amounts depend on the type of income, province, and individual corporate circumstances. Consult a qualified tax professional for advice specific to your CCPC's situation.