How to Reduce Capital Gains Tax: 9 Legal Strategies for 2025

Capital gains tax (CGT) is one of the few taxes with significant legal room for planning. Unlike income tax — where your employer deducts tax before you even see the money — CGT is largely timing-driven. When you sell, what you sell, and where you hold assets can each slash the tax owed. Here are nine strategies used by investors in the US, UK, Canada, and Australia.

1. Hold for the long-term rate threshold

This is the single most powerful CGT strategy for US investors. Assets held for more than 12 months qualify for preferential long-term capital gains rates (0%, 15%, or 20% depending on income). Short-term gains — on assets held 12 months or less — are taxed as ordinary income at up to 37%.

The difference is dramatic. A $100,000 short-term gain for someone in the 32% income bracket costs $32,000 in federal CGT. Hold the same asset 366 days (one day past the threshold) and, at 15% long-term rate, the tax drops to $15,000 — a $17,000 saving from a single calendar day's patience.

Australia mirrors this structure: assets held longer than 12 months receive a 50% CGT discount, effectively halving the tax rate on those gains. Selling at 11 months is materially worse than waiting one more month.

2. Harvest tax losses before year-end

Tax-loss harvesting means strategically selling investments that are at a loss to offset gains you've already realised elsewhere in the same tax year. Capital losses can offset capital gains dollar-for-dollar. In the US, if losses exceed gains, you can deduct up to $3,000 against ordinary income per year, with excess losses carried forward indefinitely.

Example: You realise a $20,000 gain on stock A. You're also sitting on a $15,000 unrealised loss in stock B. If you sell stock B before 31 December, your net taxable gain drops to $5,000 — potentially saving $3,000+ in CGT at the 15% rate, or much more at short-term rates.

US wash-sale rule: You cannot buy the same or "substantially identical" security within 30 days before or after the loss sale. The wash-sale rule doesn't prevent you from immediately buying a similar (but not identical) fund — selling an S&P 500 ETF and buying a total US market ETF maintains your market exposure while locking in the loss for tax purposes.

The UK allows bed and ISA or bed and SIPP — selling a holding to realise a gain or loss and repurchasing it inside a tax-sheltered account. The UK has a "30-day rule" that disallows immediate repurchase in the same account at a loss, but moving it into an ISA is a separate account and not restricted.

3. Fill your tax-sheltered accounts

Gains inside tax-sheltered accounts are exempt from CGT entirely in most jurisdictions:

• US — Roth IRA/Roth 401(k): Gains grow tax-free and qualified withdrawals are tax-free. Contributing aggressively early (especially in low-income years) allows decades of compounding with zero CGT. For 2025: $7,000/year Roth IRA contribution limit ($8,000 if 50+).
• UK — ISA: Gains inside a Stocks & Shares ISA are CGT-exempt. The annual ISA allowance is £20,000. Each year you don't use it, the allowance is gone permanently.
• Canada — TFSA: Tax-Free Savings Account contributions grow and can be withdrawn CGT-free. 2025 contribution room: $7,000/year (cumulative room since 2009 for eligible Canadians is now over $95,000).
• Australia — Superannuation: Gains on assets held in super are taxed at a maximum of 10% (concessional phase), or 0% once you're in pension phase (account balance below the transfer balance cap). Accelerating contributions can move appreciating assets into a more favourable tax environment.

4. Use your annual exemption every year (UK)

The UK's Annual Exempt Amount (AEA) is £3,000 for 2025/26 — down substantially from the £12,300 that applied in 2022/23. While this is a much smaller shield than before, it still means £3,000 of gains each year are free from CGT. Use it or lose it: unused AEA cannot be carried forward.

Investors with sizeable portfolios often sell holdings in tranches across multiple tax years to make full use of the annual exemption each year, rather than selling everything at once and paying CGT on the excess.

5. Time your realisation to a lower-income year

CGT rates are income-dependent (in the US, UK, and indirectly in Canada/Australia). If you're planning to retire, take a career break, or know you'll have a lower-income year ahead, deferring a sale can move the gain into a lower-rate bracket.

In the US, the 0% long-term CGT rate applies to gains up to $48,350 (single filer, 2025). In a low-income year — perhaps a year between jobs, or early retirement before Social Security and RMDs kick in — you might realise gains at 0% federal CGT. This "Roth conversion ladder" and "strategic gain harvesting" approach is a cornerstone of early retirement tax planning.

6. Give appreciated assets to charity

In the US, donating appreciated securities (shares, ETFs, real estate) directly to a registered charity means you never pay CGT on the built-in gain — and you get a charitable deduction for the full fair-market value. This is significantly more tax-efficient than selling first and donating cash.

Example: You hold shares with a cost basis of $5,000 now worth $30,000. Selling and donating the cash: you owe ~$3,750 CGT (at 15%), net donation = $26,250 with a deduction for $26,250. Donating the shares directly: $0 CGT, deduction for $30,000. Net tax benefit: the full $30,000 deduction, $3,750 CGT avoided.

A Donor-Advised Fund (DAF) lets you bunch several years of charitable giving into a high-income year (maximising the deduction) while directing grants to charities over time.

7. Use the primary residence exemption

Each country offers significant protection on your main home's sale:

• US: Single filers can exclude up to $250,000 of capital gain on a primary residence; married couples up to $500,000. The property must have been your main home for at least 2 of the last 5 years. Above the exclusion, gains are taxed at long-term CGT rates (assuming you held it more than a year).
• UK: Private Residence Relief (PRR) exempts gains on a property that has been your main home throughout ownership. Lettings Relief was largely withdrawn in 2020 but remains available in limited cases where the owner shares occupation.
• Canada: Gains on your principal residence are fully exempt from CGT. This is one of the most generous exclusions in the world — and one reason property investment outside the principal residence faces capital gains tax.
• Australia: The main residence exemption makes your home CGT-exempt while you live in it. Partial exemptions apply if the property was partly income-producing or was rented for a period.

8. Consider Qualified Opportunity Zone investments (US)

The US Qualified Opportunity Zone (QOZ) programme allows investors to defer and potentially reduce CGT by reinvesting capital gains into a Qualified Opportunity Fund within 180 days of the sale. Rules for 2025 and beyond have evolved; consult a tax adviser for current deferral periods and exclusion rates. QOZ investments involve real operational risk and illiquidity — they're most suitable for investors with large, confirmed gains who have appropriate risk tolerance.

9. Carry losses forward strategically

In the US, net capital losses above the annual $3,000 ordinary income offset limit carry forward indefinitely. A bad year in the market creates a "tax asset" — future carryforward losses can offset future gains when markets recover. Track your carryforward losses carefully on Schedule D; they survive from year to year and accumulate.

Canada similarly allows capital losses to be carried back 3 years or carried forward indefinitely, to be applied only against capital gains (not ordinary income). Australia allows carried-forward capital losses to offset future capital gains with no time limit.

Combining strategies: a practical example

Suppose you have a $150,000 long-term gain to realise this year (US, single filer, $95,000 other income):

1. Hold past 12 months (done): Qualifies for 15% LTCG rate, not 37% ordinary.
2. Harvest $20,000 in losses from another holding before year-end: Net gain = $130,000.
3. Donate $15,000 of appreciated shares (with $3,000 basis) to charity: Avoid $1,800 CGT, get $15,000 deduction instead. Net taxable gain = $115,000.
4. Contribute $23,500 to Solo 401(k) (if self-employed): Reduces taxable income, potentially keeping more of the gain in the 15% LTCG bracket.

Combined, these four moves reduce the taxable gain from $150,000 to roughly $91,500 — and the effective federal CGT rate could be well under 12% on the original $150,000 instead of 15–20%.

What these strategies don't cover

This guide covers federal CGT strategies. State-level CGT varies enormously — California taxes capital gains as ordinary income (up to 13.3% state rate), while Florida and Texas have no state income tax at all. Always account for state tax when planning realisation timing. In multi-asset, high-net-worth situations, estate planning strategies (step-up in basis at death) can also play a major role.