An expatriation tax or emigration tax is a tax on persons who cease to be tax resident in a country. This often takes the form of a capital gains tax against unrealised gain attributable to the period in which the taxpayer was a tax resident of the country in question. In most cases, expatriation tax is assessed upon change of domicile or habitual residence; in the United States, which is one of only two countries (Eritrea is the other) to tax its overseas citizens, the tax is applied upon relinquishment of American citizenship, on top of all taxes previously paid.
Canada imposes a "departure tax" on those who cease to be tax resident in Canada. The departure tax is a tax on the capital gains which would have arisen if the emigrant had sold assets after leaving Canada ("deemed disposition"), subject to exceptions. However, in Canada, unlike the U.S., the capital gain is generally based on the difference between the market value on the date of arrival in Canada (or later acquisition) and the market value on the date of departure.
In December 1931, the Reich Flight Tax was implemented as part of a larger emergency decree with the goal of stemming capital flight during the unstable Interbellum period. After the Nazis seized power in 1933, the Nazi government largely used the tax to confiscate assets from persecuted people (mostly Jews) who sought to flee Nazi Germany. This tax was officially repealed in 1953.
The Netherlands has treaties with Belgium and Portugal permitting them to charge emigration tax against Dutch people who move to those countries. The aim is to impose a tax on persons who move abroad and cash out on the tax-free appreciation of their Dutch pensions. However, in 2009, the Supreme Court of the Netherlands ruled that the Tax and Customs Administration could not impose an emigration tax on a Dutch man who moved to France in 2001.
The current South African exit tax regime works in concert with South Africa's foreign exchange controls. A person who is a resident of South Africa as defined under the exchange control laws (someone who is resident or domiciled in South Africa) may change status to become an emigrant, if the person is leaving the Common Monetary Area (South Africa, Namibia, Swaziland, and Lesotho) to take up permanent residence in another country. A single emigrant may expatriate up to R4 million of assets without exit charge, while a family is entitled to twice that amount. The emigrant must declare all worldwide assets to an Authorised Dealer of the South African Reserve Bank, and obtain a tax clearance certificate from the South African Revenue Service.[dead link]
In December 2014, a new 'Exit Tax' was announced which is governed by Article 95 of the Income Tax Act. This applies to departing Spanish resident taxpayers with shares worth more than four million euros or one million if they hold a stake of 25% of a single business and then transfer their habitual residence outside Spain if they have previously lived in Spain 10 of the last 15 years.
Unlike all other countries with the exception of Eritrea, the United States taxes its citizens on worldwide income, even if they are permanently resident in another country. To deter tax avoidance by abandonment of citizenship, the United States imposes an expatriation tax on some of those who give up U.S. citizenship. The tax also applies to lawful permanent residents or green-card holders who are considered "long-term residents." The Tax Code defines a long-term resident as any individual who is a lawful permanent resident of the United States in at least 8 taxable years during the period of 15 taxable years ending with the taxable year during which the expatriation occurs. 
The first law to authorize taxation of former citizens was passed in 1966; it created Internal Revenue Code Section 877, which allowed the U.S.-source income of former citizens to be taxed for up to 10 years following the date of their loss of citizenship. Section 877 was first amended in 1996, at a time when the issue of renunciation of U.S. citizenship for tax purposes was receiving a great deal of public attention; the same attention resulted in the passage of the Reed Amendment, which attempted to prevent former U.S. citizens who renounced citizenship to avoid taxation from obtaining visas, but which was never enforced. The American Jobs Creation act of 2004 amended Section 877 again. Under the new law, any individual who had a net worth of $2 million or an average income tax liability of $139,000 for the five previous years who renounces his or her citizenship is automatically assumed to have done so for tax avoidance reasons and is subject to additional taxes. Furthermore, with certain exceptions covered expatriates who spend at least 31 days in the United States in any year during the 10-year period following expatriation were subject to US taxation as if they were U.S. citizens or resident aliens.
A bill entitled Tax Collection Responsibility Act of 2007 was introduced during the 110th session of congress in July 2007 by Charles B. Rangel. It contemplated, among others, a revision of the taxation of former American citizens whose citizenship officially ends, In particular, all property of an expatriate up to certain exceptions would be treated as having been sold on the day before the expatriation for its fair market value with any gain exceeding $600,000 classified as taxable income. This bill failed to advance to the Senate.
The HEART Act, passed on 17 June 2008, created the new Section 877A, which imposed a substantially different expatriation tax from that of the earlier Section 877. The new expatriation tax law, effective for calendar year 2009, defines "covered expatriates" as expatriates who have a net worth of $2 million, or a 5-year average income tax liability exceeding $139,000, to be adjusted for inflation, or who have not filed an IRS Form 8854 certifying they have complied with all federal tax obligations for the preceding 5 years. Notwithstanding the above, certain dual citizens by birth and certain minors as defined in Section 877A(g)(1)(B) are not considered "covered expatriates". Under the new expatriation tax law, "covered expatriates" are treated as if they had liquidated all of their assets on the date prior to their expatriation. Under this provision, the taxpayer's net gain is computed as if he or she had actually liquidated their assets. Net gain is the difference between the fair market value (theoretical selling price) and the taxpayer's cost basis (actual purchase price). Once net gain is calculated, any net gain greater than $600,000 will be taxed as income in that calendar year. The tax applies whether or not an actual sale is made by the taxpayer, and whether or not the notional gains arise on assets in the taxpayer's home country acquired before immigration to the United States. It is irrelevant that the gains may have partly arisen before the taxpayer moved to the U.S.
The new tax law also applies to deferred compensation (401(a), 403(b) plans, pension plans, stock options, etc.) of the expatriate. Traditional or regular IRAs are defined as specific tax deferred accounts rather than deferred compensation items. If the payer of the deferred compensation is a US citizen and the taxpayer expatriating has waived the right to a lower withholding rate[clarification needed], then the covered expatriate is charged a 30% withholding tax on their deferred compensation. If the covered expatriate does not meet the aforementioned criteria then the deferred compensation is taxed (as income) based on the present value of the deferred compensation.
Donald Trump's 2017 tax reform has had and will continue to have huge implications for US expats who have an investment in non-US businesses. The two main new laws in place relating to Controlled Foreign Corporations (CFCs): any non-US business that is at least half owned by US shareholders, each of whom owns at least 10%.
For most, this tax will have already been paid. Payable by April 17th 2018 if the CFC had a December 31st year end date, corporate shareholders were required to pay a one-off tax of 15.5% on cash or cash-equivalent assets and 8% on non-cash assets that were accumulated after 1986 determined as of November 2, 2017, or as of December 31, 2017 (depending on which was higher). This transition to a 'territorial tax regime' means most foreign income earned by corporations in the future will not be taxed when it is moved back to the US.
While this was a daunting prospect for many US expats, they were provided with the option to pay the tax interest-free over a period of 8 years. If they elected to do so, the liability would be paid in 8 instalments beginning with 8% of the net tax liability for the first 5 instalments, 15% for the sixth, 20% for the seventh and finally ending with a 25% of the net tax liability payment to finish the obligation. This tax does not apply to previously-taxed earnings and profits but deferred foreign income. 
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- Canada Revenue Agency: Newcomers to Canada
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- Instructions to form 8854
- Notice 2009-85, Section 2(A)