Yes, your Social Security earnings count as income for federal income tax purposes. How much of that income is taxable depends on your total income and your calculated combined income. Even if it counts as income, you are not required to pay any tax on that income if you earn less than $25,000 a year. With average Social Security payments of about $18,000 per year, people whose only source of income is Social Security would not be required to pay any taxes on their benefits.
Married couples filing jointly have a slightly higher threshold of $32,000 before having to pay taxes on their Social Security benefits. However, if you have additional sources of income, such as private retirement benefits or even a job, this will likely increase the amount of your income enough to require you to pay taxes on some of your Social Security income. At most, you will be required to pay taxes on only 85% of your SS income. Therefore, there will always be a 15% portion of social security benefits that are considered tax-free.