I had a lively research project over the weekend. One of my clients was reviewing his annual Social Security statement, the one that lists yearly earnings that are credited for Social Security eligibility. And he noticed that he didn't have any income listed for several years, even though we filed all his tax returns last year. As it turns out, there's a very specific time period for reporting self-employment earnings and obtaining credit for Social Security purposes.

Now most people don't need to worry too much about this, since wages from employment are reported each year using Form W-2. Employers send the W-2s directly to the Social Security Administration, and employees get credit for their Social Security wages. Self-employed people, however, need to report their income on a Form 1040 using Schedule C; and self-employed farmers report their income on a Schedule F. And here's where the time limits come into play. To get credit for their self-employment earnings, they will need to file their tax returns within three years, three months, and fifteen days after the end of the year in which they earned their income.

In my client's particular situation, some of his returns were filed after this period. So even though we calculated his tax, and his self-employment tax, and he paid his taxes in full, he won't get credit for the tax returns that were filed after this time limit elapsed.

So if you need to file your back taxes, you will need to keep two separate time limits in mind. There's the time limit for getting credit for Social Security purposes, plus a separate 3 year time period for claiming refunds from the IRS. The difference is that the Social Security time limit expires on March 15th three years after the end of the calendar year, whereas the tax refund time limit expires on April 15th three years after the end of the calendar year.

This 3-year, 3-month, 15-day limit also applies to correcting your Social Security earnings. So one tip that applies to everyone is to check your annual Social Security statement and inform the agency of any earnings that seem to be missing before the time period has elapsed.

This week we've heard from not just one, but two About.com readers on the forum who are dealing with foreign wages. One is living in Australia, and the other reader is working in the US for a Canadian employer. Both asked a question I hear frequently: do you need to file returns in the USA if all your income is earned abroad?

The answer, not surprisingly, is yes. But US citizens working abroad have several tax breaks available to them to ease the burden of filing in two countries. In the US they may be able to exempt some or all of their foreign wages from US income taxes, up to $87,600 for 2008. This tax break is called the foreign earned income exclusion, and it applies only to foreign wages or self-employment income.

Another benefit available is the foreign tax credit. This is a credit against US income taxes for taxes paid to foreign governments. The credit applies to any type of foreign income, such as wages, interest or dividends. The foreign tax credit is a handy tax break for investors too, who might have paid foreign taxes on stocks or mutual funds with foreign holdings.

In addition to these two basic tax breaks for taxpayers with foreign income, the US also has tax treaties with various countries around to world. These treaties specify how certain types of income are going to be taxed. In the case of the reader working for a Canadian employer, that treaty specifies conditions under which wages will be taxed only in one country.

People working, living, or doing business abroad have one final consideration, and that's reporting any bank accounts they have outside the United States. This is an annual report submitted to the Treasury Department. The Treasury uses these reports as part of its ongoing efforts to combat money laundering. US citizens must file this report if their total balance in all foreign bank accounts is $10,000 or greater at any time during the year.