It's a date Americans have learned to dread: April 15. Tax day.

In preparation, the U.S. Internal Revenue Service sent a consultant to the embassy in Moscow for four days to help American citizens living here to navigate the tricky waters of expatriate taxation. There were not, of course, enough appointment slots to go around.

In Russia, too, tax day is approaching. Travelers on the metro are kindly reminded over the public address system to file. And that means expatriates, too.

According to experts at Tandem Financial Law Consultants, a Moscow firm specializing in taxes, most foreigners working in Russia will find that they will have to pay their taxes here rather than in their home country. And visitors from Washington, unfortunately, can't help much with that.

Under Russian law, anyone residing in the country for more than 183 days out of the year is required to pay income and other personal taxes here. That, however, can conflict with other countries' laws. U.S. law, for example, requires anyone residing in the U.S. for more than only 28 days to pay taxes there.

To get around that problem, Russia has signed taxation treaties with most major countries, stipulating that a citizen of one of the countries generally has to pay taxes only to one country. Generally, those treaties also set a 183-day threshold. There are, however, some notable exceptions, countries with whom Russia has not signed such treaties, including China and Japan, according to Tandem.

So, anyone living here more than half of the year has to pay Russian taxes. Again, there is a notable exception: diplomats, who pay taxes only in their home country.

As a rule, anyone employed by a Russian company or a Russian affiliate of a foreign company will have their income tax withheld from their salary and paid directly to the government. But that does not absolve the taxpayer from the task of paying taxes. Any other transactions, whether from independent contract work, local investments, real estate or any other source, must be reported for taxation by the individual.

And when that is done, foreigners must go to their local tax inspectorate for a document proving that taxes were paid here. That must then be presented to the tax authority in the person's home country, to prove that taxes were paid abroad and thus are not owed at home.

However, other taxes may still be owed at home. Chiefly, those would come from investments or transactions that take place in the home country, such as stock dividends or the sale of real estate.

And there are still gray areas, particularly for those who receive their income directly into a bank account held outside Russia, especially if that income comes from an account that is also located outside Russia. According to Tandem, Russian tax authorities are not capable of tracking such income, though they do expect that income to be declared for taxation here. In some cases, however, other countries may consider that income to be taxable there as well, according to Tandem.

To be safe, it's best to declare such off-shore income in one country or another, to be protected against tax audits, especially if it makes up the bulk of your income, according to Tandem. And though it may be simpler to declare such income at home, especially for EU citizens, it may be cheaper to pay taxes on it here, Tandem said.