Provisional income helps determine if you owe taxes on Social Security benefits. To calculate it, start with your adjusted gross income (AGI), which includes wages, retirement income, and interest. Add any tax-exempt interest and half of your Social Security benefits. Then, compare this total against income thresholds. For singles, if provisional income is under $25,000, benefits are tax-free. Between $25,000 and $34,000, up to 50% is taxable; above $34,000, up to 85% may be taxed. For married couples, if combined income is under $32,000, benefits are usually tax-free. Between $32,000 and $44,000, up to 50% may be taxable, and above $44,000, up to 85% could be taxed. Knowing this helps with retirement financial planning.