A study from the Employee Benefit Research Institute says that four out of every 10 of the nation's retirees depend on Social Security for most of their monthly income, and this year Social Security is raising the age at which people qualify for full benefits and raising the taxes for some self-employed individuals and for those with higher incomes. Beneficiaries will get a 1.4 percent cost-of-living increase, but some of that will be lost in the higher deduction for Medicare coverage; the changes should alert workers to the fact that Social Security is a supplement for retirement, not a mainstay. The Social Security Administration says that the average worker can probably expect a retirement benefit that is equal to about 40 percent of average lifetime earnings.