What income sources are included in combined income for Social Security?

1. Why combined income matters — the high-stakes test that can turn benefits taxable

Combined income is the statutory yardstick that triggers taxation of Social Security benefits and influences planning for retirees on fixed incomes. The combined-income formula adds three elements: adjusted gross income, non-taxable interest, and half of the Social Security benefits; those elements together establish whether benefits are subject to federal income tax and at what percentage — typically 50% or up to 85% of benefits can be taxable depending on where combined income falls relative to set thresholds. This matters because many common retirement income sources — such as wages from part-time work, required minimum distributions from retirement accounts, taxable interest from savings, and pension payments — increase AGI and thereby increase combined income and the likelihood that a portion of benefits becomes taxable. ^{[1] [2] [3]}

2. The concrete thresholds that change the tax picture for single people and couples

The taxation framework applies two tiers to combined income: a lower threshold where up to half of benefits may be taxable and a higher threshold where up to 85% may be taxable. For single filers, partial taxation begins when combined income exceeds $25,000, and a larger portion becomes taxable once combined income exceeds $34,000. For married couples filing jointly, those trigger points are $32,000 and $44,000, respectively. If combined income is below the lower thresholds, Social Security benefits are not taxed at the federal level. Taxpayers should also know that these thresholds are statutory breakpoints used by the IRS and Social Security Administration to compute tax owed and can interact with state tax rules, which vary and can tax Social Security differently. ^{[1] [2] [3]}

3. What counts toward AGI — the usual suspects that push benefits into taxable territory

Adjusted gross income is the broad base in the combined-income formula and includes wage income, self-employment earnings, taxable portions of pensions and annuities, distributions from traditional IRAs and 401(k)s (unless rolled over), capital gains, taxable interest, rental income, and certain miscellaneous income like unemployment benefits. Employer-sponsored retirement withdrawals and regular wages are the most common drivers of higher AGI in retirement. Because AGI is the largest single component of combined income, small changes—such as working part-time, taking larger IRA distributions to meet living expenses, or realizing capital gains—can materially increase combined income and therefore the taxable share of Social Security benefits. Tax planning often focuses on managing AGI precisely because it directly affects combined income. ^{[1] [2] [3]}

4. Nontaxable interest, half of benefits, and the edge cases people miss

Nontaxable interest (for example, certain municipal bond interest that is excluded from federal taxable income) still counts in combined income even though it is not taxed in normal income tax calculations. Likewise, the formula explicitly uses one-half of Social Security benefits in the combined-income sum, which can create non-intuitive results: increasing other income can make a greater portion of benefits taxable, and sometimes converting tax-exempt income into taxable income (or vice versa) changes combined income more than expected. Edge cases include workers’ compensation and VA benefits (generally excluded from AGI), and Roth IRA distributions (generally excluded from AGI if qualified), which can substantially change combined-income calculations and thus the taxability of Social Security. ^{[1] [2] [3]}

5. Practical implications and planning levers retirees should watch

Because combined income aggregates multiple income streams, retirees can influence taxability through timing and source choices: delaying IRA withdrawals, converting traditional IRA balances to Roth IRAs in low-income years, managing capital gains realization, or limiting wage income can keep combined income below taxing thresholds. Conversely, unplanned part-time wages or larger-than-expected pension payments can push combined income over the thresholds. State tax rules and filing status also matter: married filing separately often leads to worse tax treatment for Social Security, and some states tax Social Security benefits differently. Taxpayers should model combined income across likely income scenarios to understand how each revenue source moves the needle on benefit taxation. ^{[1] [2] [3]}