Alternative Minimum Tax: The Lifetime Exemption Shelters 70% of Your Gain, Not All of It
Most people will never pay the alternative minimum tax, and the reason is a single number. The minimum tax ignores the first $181,440 of adjusted taxable income in 2026, so a salary on its own does not reach it and a dividend portfolio rarely does. What reaches it is the one-time gain that the regular return barely taxes, because the minimum tax is built by putting back exactly the deductions and exemptions that shelter such a gain. The sharpest case is the lifetime capital gains exemption. On a qualifying sale it removes 100% of the gain from the regular calculation and 70% of it from this one.
You Compute the Tax Twice and Pay the Higher Figure
That is the whole architecture, and the Act says so in its first line. Section 127.5 of the Income Tax Act turns on one comparison: “where the amount that, but for section 120, would be determined under Division E to be an individual’s tax payable for a taxation year is less than the amount determined under paragraph (a) … the individual’s tax payable under this Part for the year is the total of …”
The second figure, the minimum amount, comes from section 127.51 of the Income Tax Act as a formula: A(B – C) – D. A is 20.5%. B is adjusted taxable income, defined by section 127.52 of the Income Tax Act. C is “the first dollar amount for the year referred to in paragraph 117(2)(d)”, which is the start of the fourth federal bracket. D is the basic minimum tax credit from section 127.531 of the Income Tax Act. Both of those sections carry the 2024 redesign on their face: s.127.51 was amended by 2024, c. 17, s. 40, and s.127.531 by s. 42 of the same Act.
C is worth pinning down, because it is the exemption that keeps ordinary filers out. The consolidation of 117(2)(d) carries $177,882, and CRA’s Form T691 prints 177,882.00 on line 94 as the basic exemption for 2025. For 2026 the CRA indexation adjustment table sets the taxable income above which the 29% bracket begins at $181,440. That is the threshold adjusted taxable income has to clear before any of this costs a dollar.
What the Minimum Tax Puts Back
Adjusted taxable income is ordinary taxable income with a specific list of shelters stripped out or reduced. The list is the article.
| What it is | Regular tax | Minimum tax |
|---|---|---|
| A capital gain | Half of it is taxable | All of it, s.127.52(1)(d), where the fraction is read as “1/1” |
| The capital gain on donated publicly listed securities | None of it is taxable | 30% of it, s.127.52(1)(d.1) read as “3/10”; T691 line 26 prints “× 30%” |
| The lifetime capital gains exemption | Shelters the whole taxable half | Allowed at 7/5 of the claim under s.127.52(1)(h)(ii), which leaves 30% of the gain in the base |
| The 50% employee stock option deduction, s.110(1)(d) | Halves the benefit | Not allowed at all. s.110(1)(d) is absent from the list in s.127.52(1)(h), and T691 lines 28 to 32 add back the full of T4 boxes 39 and 91 |
| Interest on money borrowed to invest, and investment counsel fees | Fully deductible | Half, s.127.52(1)(j)(ii); T691 lines 64 to 68, applicable rate 50% at line 79 |
| Non-capital losses carried from other years | Fully deductible | At most half, s.127.52(1)(i), which allows the lesser of half the amount deducted and a recomputed total |
| An eligible dividend | Grossed up, then the dividend tax credit comes off | Neither. The gross-up is removed under s.127.52(1)(f), with T691 backing out 27.5362% for eligible and 13.0435% for other than eligible, and s.121 is not among the credits s.127.531 allows |
| The donation tax credit | Claimed in full | 80% of it, s.127.531(c) read as “4/5”; T691 line 99 |
| Most other non-refundable credits, including the basic personal amount | Claimed in full | 50% of them, s.127.531(a) and (b) read as “1/2”; T691 line 98 |
Provisions from the Income Tax Act, Justice Laws, act current to September 21, 2026, last amended June 18, 2026. Form line references from CRA Form T691 for 2025.
The two credit fractions at the bottom are different on purpose, and it is worth not flattening them: donations survive at 80%, everything else at 50%.
An Ordinary Gain With No Exemption Reaches It Too
The 100% inclusion in s.127.52(1)(d) reaches an ordinary capital gain as a matter of rate, not as a shelter being clawed back, so a filer who holds nothing but public-market shares and claims no exemption of any kind meets the same arithmetic. Same 2026 filer with $60,000 of other income, and one large disposition with nothing sheltering it.
| Capital gain | Regular federal tax | Minimum amount | Owed on top |
|---|---|---|---|
| $250,000 | $35,672.55 | $25,208.41 | $0.00 |
| $500,000 | $74,199.99 | $76,566.77 | $2,366.78 |
| $750,000 | $115,449.99 | $127,816.77 | $12,366.78 |
| $1,000,000 | $156,699.99 | $179,066.77 | $22,366.78 |
| $2,000,000 | $321,699.99 | $384,066.77 | $62,366.78 |
Minimum tax first arises at a gain of $440,831. Below that there is nothing to pay, and above it what drives the bill is the size of the single disposition, not anything the filer claimed. What an exemption changes is not whether the minimum tax reaches a gain but how much of it, and the lifetime capital gains exemption is the sharpest case of that.
A $1,275,000 Sale the Exemption Covers Completely Still Costs $46,059.32
Take an Ontario resident in the 2026 tax year who sells qualified small business corporation shares for a capital gain of $1,275,000, which is exactly the 2026 lifetime capital gains exemption limit. Other income for the year is $60,000. On the regular return the sale is nearly free. The figures below are federal income tax except where Ontario is named, and the example gives the filer the basic personal amount as their only credit, which net income of $697,500 grinds from $16,452 down to $14,829 at a cost of $227.22 at the 14% credit rate.
| Regular tax | Amount |
|---|---|
| Other income | $60,000.00 |
| Capital gain | $1,275,000.00 |
| Taxable capital gain, one half | $637,500.00 |
| s.110.6 capital gains deduction | $637,500.00 |
| Net income | $697,500.00 |
| Taxable income | $60,000.00 |
| Federal tax before credits | $8,496.01 |
| Basic personal amount | $14,829.00 |
| Credit at 14% | $2,076.06 |
| Regular federal tax | $6,419.95 |
Now the same year run through Part 1 of T691.
| The minimum amount | Amount |
|---|---|
| Taxable income | $60,000.00 |
| Add the non-taxable half of the gain | $637,500.00 |
| Subtract the extra capital gains deduction, 40% of line 25400 | $255,000.00 |
| Adjusted taxable income | $442,500.00 |
| Less the basic exemption | $181,440.00 |
| Net adjusted taxable income | $261,060.00 |
| Gross minimum amount at 20.5% | $53,517.30 |
| Credits allowed at 50% | $1,038.03 |
| Minimum amount | $52,479.27 |
Our arithmetic, on the s.127.51 formula and the T691 line order, with the 2026 exemption of $181,440 and the $1,275,000 limit from CRA’s indexation adjustment table.
The minimum amount is the larger of the two, so the filer pays an additional $46,059.32 federally on a sale the regular system treated as tax free. Ontario then adds $11,344.41 of basic additional tax on top of that, and the Ontario surtax is charged on the addition as well.
The 7/5 fraction is where the number comes from. The gain enters the base at 100%, or $1,275,000, and the capital gains deduction is allowed at 7/5 of $637,500, which is $892,500. The difference is $382,500, exactly 30.0% of the gain. That is the sentence worth keeping: the lifetime exemption shelters 70% of a qualifying gain against the minimum tax, not all of it.
One line on the form reads backwards unless you watch it. Line 87 says “Lifetime capital gains exemption: enter the amount from line 25400 of your return × 40%”, and it is subtracted, not added. Taxable income already had the full $637,500 deduction; the form adds the other half of the gain back and then hands over a further 40% of $637,500 so that the total allowed comes to 7/5. That $255,000 line lowers the bill.
With $60,000 of other income, a gain fully covered by the exemption produces no minimum tax at all until it reaches $526,068. Below the crossover there is nothing owed: at a gain of $400,000 the minimum amount is $0.00 against regular tax of $6,419.95. At $600,000 the minimum amount is $10,966.77 and $4,546.82 is owed on top. At $1,000,000 it is $35,566.77 and $29,146.82.
The Bill Peaks on an Ordinary Income and Fades at the Top
This is the part that runs against intuition. Hold the $1,275,000 sheltered gain constant, vary the seller’s other income, and the seller who escapes is the high earner, not the low one.
| Other income | Regular federal tax | Minimum amount | Owed on top |
|---|---|---|---|
| $0 | $0.00 | $40,179.27 | $40,179.27 |
| $60,000 | $6,419.95 | $52,479.27 | $46,059.32 |
| $150,000 | $26,682.47 | $70,929.27 | $44,246.80 |
| $300,000 | $70,899.99 | $101,679.27 | $30,779.28 |
| $450,000 | $120,399.99 | $132,429.27 | $12,029.28 |
| $600,000 | $169,899.99 | $163,179.27 | $0.00 |
The shape has three parts. While regular tax is still in the 14% band the amount owed climbs, from $40,179.27 with no other income at all up to $46,059.32. Then it stops, because the worst case is not a point, it is a plateau: right across the 20.5% federal bracket, which runs from $58,523 to $117,045 of other income in 2026, the two schedules climb at the same rate and the amount owed does not move at all, $46,059.32 at both ends and everywhere between. Above the plateau the regular schedule moves to 26, then 29, then 33 while the minimum amount keeps climbing at a flat 20.5%, so regular tax gains ground, and once other income clears $546,234 there is no minimum tax left to pay.
The same $1,275,000 sheltered gain against the seller’s other income for 2026. Our arithmetic, federal income tax only, with the basic personal amount as the only credit.
Donated Securities Keep 30% of the Gain in the Base
Section 38 of the Income Tax Act makes a taxable capital gain “½ of the taxpayer’s capital gain” at paragraph (a), then sets it “equal to zero” at paragraph (a.1)(i) where “the disposition is the making of a gift to a qualified donee of a share, debt obligation or right listed on a designated stock exchange”. Giving the securities in kind rather than selling them and donating cash is what buys that zero. The minimum tax does not follow it all the way: s.127.52(1)(d.1) puts 30% of the gain into the base, and s.127.531(c) trims the donation credit to 80%. In rate terms, 30% of a dollar of gain taxed at 20.5% is 6.15 cents of gross minimum amount per dollar of gain, before the exemption and before any credits come off. A donated gain that is the only thing lifting adjusted taxable income has to reach $604,800 before it so much as touches the $181,440 exemption, because 30% of $604,800 is $181,440, and the more other income the donor has the lower that figure goes. We have made the case for donating the shares rather than selling them first and it still holds. The qualifier this adds is that the gain the donor avoids on the regular return is not avoided in full on the minimum one.
The Stock Option Deduction Does Not Survive At All
The 50% security options deduction in s.110(1)(d) is simply absent from the list of deductions s.127.52(1)(h) preserves, and T691 lines 28 to 32 add back the total of T4 boxes 39 and 91 in full. What enters the minimum tax base is the full option benefit rather than half of it, and it enters a base that is already counting 100% of any capital gain realised in the same year, which is why a large tranche exercised in the year of a sale is the dangerous combination. The mechanics of that exercise, and how it differs from an RSU vesting, are set out in our guide to the tax on employee stock options and RSUs.
Spreading the Gain Over Five Years Removes It Here
Run the same $1,275,000 gain as five equal annual slices of $255,000 and the result changes completely. Taxable income stays at $60,000 each year, adjusted taxable income works out to $136,500, and that is below the $181,440 exemption. Minimum tax is $0.00 in each of the five years, and $0.00 across the five. That is arithmetic on this example rather than general advice, because a reserve is only available where the terms of the sale support one, which is the point our explainer on the capital gains reserve turns on.
Ontario Charges Its Own Layer on Top
The province piggybacks on the federal computation. CRA’s Worksheet ON428 calculates line 72 of Form ON428 in steps. Step 1, “Ontario basic additional tax”, takes the amount from line 11 of Part 5 of Form T691 and multiplies it by 24.63%. That is the $11,344.41 in the worked example, and step 1 is all it is. Step 2 then brings in the Ontario surtax already computed and recomputes it on the larger figure, so the surtax applies on top of the additional minimum tax as well. The 2025 worksheet sets those surtax thresholds at $5,710 and $7,307. Form ON428 also instructs that the Ontario tax reduction is not available where there is an amount on line 72.
Seven Years to Earn It Back, and Nothing in the Year of Death
The minimum tax is a prepayment rather than a surcharge, at least on paper. Section 120.2 of the Income Tax Act allows a later-year deduction for additional taxes paid “for the 7 taxation years immediately preceding the particular year that was not deducted” already, and 120.2(1)(b) caps it at the amount by which that year’s regular tax exceeds that year’s minimum amount.
For the filer who keeps earning, nearly all of it comes back. Assume our seller returns to $60,000 of ordinary income and realises nothing further. Adjusted taxable income is then $60,000, below the $181,440 exemption, so the minimum amount for that year is $0.00 and the whole of the year’s regular federal tax is available. That tax is $6,192.73, slightly below the $6,419.95 in the year of sale because with no capital gain net income falls back and the basic personal amount returns to the full $16,452. Over the seven years s.120.2(1)(a) allows, $43,349.11 of the $46,059.32 comes back and $2,710.21 never does, so 94.1% of it is recovered.
The warning is for the other seller. A founder who sells and then lives off the proceeds at a modest income may never generate a year of regular tax for the credit to attach to, in which case the seven years run out and the money is gone.
One exemption is absolute. Paragraph 127.55(c) provides that section 127.5 “does not apply in respect of … an individual for the taxation year in which the individual dies”, and CRA repeats it in plain English on page 1 of T691: “Alternative minimum tax does not apply to a person who died in 2025 or to returns filed under subsections 70(2) or 150(4), or under paragraphs 104(23)(d) or 128(2)(e) of the Income Tax Act.” A deemed disposition at death prices an entire lifetime of unrealised gain into a single year, which is precisely the shape of event this tax is built to catch, and the year of death is lifted out of it entirely. Regular tax is not lifted out, and the bill that one produces on a final return is what we walk through in how capital gains are taxed at death.
Disclaimer: The content on bestcanadianstocks.ca is for informational and entertainment purposes only and does not constitute financial advice. Past performance is not indicative of future results. Always consult a qualified financial advisor before making investment decisions. The structure of the minimum tax is quoted from the Income Tax Act on Justice Laws, act current to September 21, 2026 and last amended June 18, 2026: section 127.5 for the obligation, section 127.51 for the formula A(B – C) – D with A at 20.5%, section 127.52 for adjusted taxable income (the 1/1 capital gains fraction at (1)(d), the 3/10 fraction for donated listed securities at (1)(d.1), the removal of the dividend gross-up at (1)(f), the closed list of surviving deductions at (1)(h) which omits paragraph 110(1)(d), the lesser-of limit on loss carryovers at (1)(i) and the half deductions at (1)(j)), section 127.531 for the basic minimum tax credit at 1/2 and 4/5, section 127.55(c) for the year of death, section 120.2 for the seven-year carry-over, section 117(2) for the rates and the $177,882 fourth-bracket threshold as consolidated, and section 38(a) and (a.1)(i) for the taxable capital gain fractions. The form line order, the printed 20.5% rate, the 177,882.00 basic exemption, the 30% donated-securities line, the full add-back of T4 boxes 39 and 91, the 50% applicable rate, the 40% lifetime capital gains exemption line, the 27.5362% and 13.0435% gross-up reversals and the 50% and 80% credit lines are from CRA Form T691 for 2025, retrieved October 15, 2026. The Ontario basic additional tax rate of 24.63%, the surtax step and the 2025 surtax thresholds of $5,710 and $7,307 are from CRA Worksheet ON428 for 2025, retrieved the same day; the instruction that the Ontario tax reduction is unavailable where there is an amount on line 72 is from Form ON428. The 2026 figures, being the $181,440 basic exemption (the taxable income above which the 29% bracket begins), the $58,523, $117,045 and $258,482 bracket thresholds, the $16,452 and $14,829 basic personal amounts and the $1,275,000 lifetime capital gains exemption limit with its $637,500 deduction limit, are from the CRA indexation adjustment table, retrieved October 15, 2026. Every dollar figure in the worked examples, the two charts, the crossover at $526,068, the plain-gain threshold at $440,831, the plateau of $46,059.32 across the 20.5% bracket, the vanishing point at $546,234, the five-year reserve result and the carry-forward recovery is our own arithmetic on those rates, federal income tax only except where Ontario is named, net income taken as stated, and claiming only the basic personal amount. The arithmetic was run by a script that first checks eleven of these constants against the Act and the CRA documents, and against each other, before computing anything. No 2026 Ontario bracket, surtax threshold or basic personal amount was used, so no combined federal and Ontario total is published.
