We received social security benefits this year that were back pay for prior years. Do we refile our returns for prior years? Are the back benefits paid in this year for past years taxable for this year?

You must include the taxable part of a lump-sum (retroactive) payment of benefits received in the current year in your current year's income, even if the payment includes benefits for an earlier year.

Generally, you use your current year's income to figure the taxable part of the total benefits received in the current year. However, you may be able to figure the taxable part of a lump-sum payment for an earlier year separately, using your income for the earlier year. You can elect this method if it lowers the taxable portion of your benefits. Refer to Publication 915, Social Security and Equivalent Railroad Retirement Benefits, for a detailed explanation of the election and worksheets.

For an American citizen residing in Canada using Form 1040A, should the taxable amount of U.S. social security benefits shown on line 14b be $0.00 due to the Canada-U.S. tax treaty?

Under the 1997 protocol to the Canada - U.S. tax treaty, the Canadian and U.S. governments agreed to return to a residence-based system under which social security benefits are taxable exclusively in the country where the recipient resides. As a result, the entry for line 14b would be $0.00.

In addition to U.S. Social Security, I also receive British Social Security. How should I report the British Social Security income?

Under the U.S. United Kingdom income tax treaty that entered into force during 2003, social security income is taxable only by the country of residence. If you are a resident of the U.S. for tax purposes, the income would be reported and taxed in the U.S. You would not treat the income as U.S. social security benefits. The entire amount would be taxable as pension and annuity income on your U.S. tax return. Your "investment in the contract" for purposes of determining the portion of each payment that is taxable would be $0. Under the prior treaty with the UK, social security benefits were treated the same way.

I retired last year, and started receiving social security payments. Do I have to pay taxes on my social security benefits?

To determine whether any of your benefits are taxable, compare the base amount for your filing status with the total of one half of your social security payments plus all your income from other sources, including tax exempt interest. If you are married and file a joint return, you must combine your incomes and your social security and equivalent tier 1 railroad retirement benefits when figuring the taxable portion of the benefits.

The taxable amount of the benefits is figured on a worksheet in the Form 1040 or 1040A instruction book, or in Publication 915, Social Security and Equivalent Railroad Retirement Benefits. Refer to Tax Topic 423, Social Security and Equivalent Railroad Retirement Benefits, for base amounts, and additional information regarding taxability and reporting requirements.