One of the causes of the present crisis in the eurozone has been the failure of European government to collect all taxes levied on citizens and companies.

In Greece, Italy and Spain, tax avoidance became notorious. Rich Greek shipowners managed their businesses to minimize taxes. Foreign tax havens welcomed the rich with open arms and red carpets. Clever accountants and lawyers thought up ever more convoluted schemes enabling the wealthy and the not-so-wealthy to avoid paying taxes at specified rates.

In Spain it was said that it was normal practice for the purchaser of a house to pay a proportion in cash that was not declared and thus not subject to tax. The black economy, where services are provided in return for cash, which is not declared on tax returns and avoids value-added tax, has spiraled, while governments' budgetary deficits have grown. In some European countries, the taxpayer and the tax authorities negotiated the tax to be paid.