Social Security benefit timing and its tax consequences

Clients often ask, “What age is best to start claiming Social Security benefits?” From a tax standpoint, there is no single answer. A client still earning wages may find that waiting reduces the overlap between salary and benefits. Someone with little other income may claim earlier and owe little or no federal tax on the benefits.

The client’s tax bill is only one piece of the retirement decision. A useful starting point for the tax professional is to model what the client keeps under different initial claiming dates, then compare that with the income needed while waiting. A smaller tax bill is not much of a win if the household is short on cash.

Some clients may also arrive with a version of “Social Security isn’t taxed anymore.” The enhanced senior deduction available for 2025 through 2028 can reduce taxable income for eligible clients age 65 or older. Remind them that it did not repeal the federal rules that determine how much Social Security is included in income.

Age doesn’t decide the tax bill

Unfortunately, reaching full retirement age does not magically make Social Security benefits tax-free. To determine federal taxability under §86, start with the client’s modified adjusted gross income (MAGI), add tax-exempt interest and then add 50% of Social Security benefits. Certain exclusions, including foreign earned income and qualified U.S. savings bond interest, require additional adjustments.

• For single filers, benefits generally begin to become taxable when combined income exceeds $25,000.
• The starting point is $32,000 for married couples filing jointly (MFJ).
• Once combined income exceeds $34,000 for single filers or $44,000 for joint filers, up to 85% of benefits may be taxable.
  • This is the share included in income, not an 85% tax rate.
• Married filing separately (MFS) requires special attention, particularly when the spouses lived together during the year.

Consider a single client receiving $24,000 in annual benefits and $12,000 of other income, with no tax-exempt interest or other adjustments. Combined income is $24,000, so none of the benefits is federally taxable. Add a $10,000 fully taxable IRA withdrawal and combined income becomes $34,000. At that point, $4,500 of the Social Security benefits is taxable.

Reference NATP’s blog, When are your client’s Social Security benefits taxable?, for a closer look at determining the taxable portion of benefits.

Build a tax-savvy Social Security strategy

The years around retirement can create planning opportunities. If work stops before Social Security begins, a lower-income window may be a good time to model a Roth conversion or planned IRA withdrawal, weighing today’s tax cost against future income.

Health coverage can push the answer in another direction. For clients buying Marketplace coverage before Medicare, premium tax credit MAGI includes nontaxable Social Security benefits. Once Medicare begins, higher MAGI can trigger IRMAA for Parts B and D. Those premiums generally use tax information from two years earlier.

For married clients filing jointly, Social Security taxability is based on both spouses’ income and benefits. The comparison should also account for household cash flow and survivor benefits rather than treating the lowest current tax bill as the best result.

Map your client’s tax situation before they claim

A tax professional can start the conversation with a simple comparison:

So, when should your tax client start Social Security?

The tax professional’s job is not to choose the Social Security benefit for the client, but to show how each claiming scenario changes taxes and available cash. Benefit-specific questions can then go back to SSA or the client’s retirement adviser.

For a deeper look at how retirement income fits together, explore NATP’s Retirement Income Taxation – Rules, Distributions and Planning webinar on Oct. 9, 2026. The webinar is also available on demand after the live event.