International notes and common audit triggers

Education, not tax advice: rules, rates and thresholds change every year, so confirm anything you plan to act on with a qualified tax professional in your own jurisdiction.

This course is US-centric because the US rules are the most detailed and most automated. Traders elsewhere meet the same concepts (character, holding period, basis, anti-avoidance) under different names. This lesson sketches four jurisdictions in broad strokes, then closes with the patterns that draw examination attention in the US. Every non-US figure is a snapshot; treat it as orientation, then check locally.

United Kingdom

Capital gains tax (CGT) applies to shares, ETFs, CFDs and crypto. There is an annual exempt amount (cut sharply in recent years to a few thousand pounds) and, above it, rates that depend on the income band; the rates were raised in the 2024 Autumn Budget. Check current figures.
Spread betting profits are treated as gambling and are not taxable; symmetrically, losses are not deductible. This is why spread betting dominates UK retail trading and does not exist in the US.
CFDs fall under CGT (or income tax if HMRC views the activity as a trade, a position it rarely takes for individuals).
The 30-day rule ("bed and breakfasting") is the wash-sale equivalent: shares sold and repurchased within 30 days are matched to the repurchase rather than the Section 104 pooled average cost. Different mechanics, similar intent.
ISAs shelter gains and dividends entirely, within annual contribution limits.
Crypto is under CGT with pooling; staking and airdrop rewards can be income.

Canada

Historically 50% of a capital gain is included in income and taxed at marginal rates (a proposal to raise the rate on large gains was announced, then cancelled; confirm the current figure).
Frequent, short-term trading can be reclassified by the CRA as business income, 100% taxable, with losses fully deductible. The factors resemble the US trader tests.
The superficial loss rule denies a loss if the same property is acquired within 30 days before or after and still held at the end of that period, including by a spouse or a controlled corporation; the denied loss is added to the replacement's basis.
TFSA gains are tax-free, but the CRA has taxed TFSAs used for frequent day trading as businesses. RRSP trading is sheltered until withdrawal.

Australia

Capital gains are added to assessable income at marginal rates; assets held more than 12 months by an individual get a 50% CGT discount.
The ATO distinguishes a share trader (a business; gains are ordinary income, losses fully deductible) from a share investor (CGT with the discount), using the familiar bundle of repetition, volume, organization and intent.
There is no statutory wash-sale rule, but ATO guidance treats sell-and-rebuy schemes done for the loss as wash sales caught by the general anti-avoidance provisions.
Crypto is a CGT asset; swaps are disposals. The tax year runs July 1 to June 30.

European Union (broad strokes)

There is no EU-wide regime; each state sets its own:

Germany: a flat tax on capital income (25% plus surcharges); crypto held over one year has been exempt on disposal; derivative losses have had capped deductibility.
France: a flat tax ("PFU") of about 30% on most financial gains, with an option for progressive rates.
Netherlands: no tax on realized gains for most individuals; instead an annual tax on a deemed return on net wealth ("Box 3"), which the courts have forced the government to reform.
Belgium: long free of CGT for private investors, but a capital gains tax on financial assets was legislated to begin in 2026.

Everywhere: three universal questions

What is the character of the gain (capital, income, business, exempt)?
What is the holding period effect, if any?
What is the anti-avoidance rule for selling and rebuying?

Those three, answered for your country from an official source, get you most of the way.

US audit triggers for traders

The IRS selects returns mostly by computer matching and statistical scoring. Patterns that raise the score for traders:

1099 mismatches. Any 1099-B, 1099-DA, 1099-NEC or 1099-DIV not reflected on the return, or a Form 8949 total that does not reconcile to the brokers' proceeds. The most common trigger and the most avoidable.
Answering "no" to the digital asset question while an exchange reports activity.
Schedule C losses year after year from a "trading business" with thin activity; hobby-loss and trader-status arguments both apply.
Large TTS deductions relative to trading income, and round numbers in place of actual figures.
Unreported foreign accounts. A foreign forex broker, prop firm or exchange account may require an FBAR (FinCEN Form 114) once aggregate foreign balances exceed $10,000 at any point in the year, and Form 8938 at higher thresholds. FBAR penalties are severe relative to the tax involved. Crypto on foreign exchanges is not currently FBAR-reportable, but FinCEN has signaled an intention to change that.
A 475 election claimed without a documented, timely election or without trader status.
Zero-basis sales left uncorrected, producing a phantom gain and then a large swing on amendment.

Numbers. A trader's two 1099-Bs total $840,000 of proceeds; the return's Form 8949 shows $790,000 because one account was forgotten. The computer sees $50,000 of unreported proceeds with zero basis and proposes tax on all of it: at an illustrative 24% rate, a $12,000 notice for what was actually a $1,500 gain. The fix is a response with the basis records; the prevention is reconciling every form before filing.

The defense for every item is the same: reconcile every form, keep the decisions file, and be able to show the counts behind any status claim.

Key idea: Every jurisdiction asks the same three questions (character, holding period, anti-avoidance) with its own answers; the UK, Canada, Australia and EU states differ sharply, so orient here and confirm locally. In the US, most examinations start from a form that did not match the return.

Try it: If you trade outside the US, write your country's answers to the three universal questions from an official source, with the date you checked. If you trade in the US, list every tax form you expect this year and confirm you know which line each maps to. Both lists take under an hour.

Recap

UK: CGT with an annual exemption and a 30-day matching rule; spread betting is tax-free with non-deductible losses; ISAs shelter gains.
Canada: partial inclusion of gains, business-income reclassification for frequent traders, the superficial loss rule, TFSA day-trading risk.
Australia: 50% discount over 12 months, share trader versus investor, anti-avoidance treatment of wash sales, July–June tax year.
EU: per-country regimes from flat taxes to deemed-return wealth taxes; check locally.
US triggers: form mismatches, the digital asset checkbox, thin-activity Schedule C losses, oversized deductions, unreported foreign accounts, uncorrected zero-basis sales.