Turning 65 changes your federal taxes in several concrete ways: you get a larger standard deduction, you qualify for a new enhanced senior deduction worth up to $6,000, your Social Security benefits may become partly taxable, your Medicare premiums become deductible, and you lose the ability to contribute to a Health Savings Account once Medicare coverage starts. Some of these kick in automatically; others require you to act. Here is how each one works and what it means for what you owe.
A Bigger Standard Deduction
Federal law adds an extra amount to the standard deduction for every taxpayer who reaches 65.1Office of the Law Revision Counsel. 26 USC 63 – Taxable Income Defined For the 2026 tax year, the additions are:
- Single or head of household: extra $2,050
- Married filing jointly, one spouse 65 or older: extra $1,650
- Married filing jointly, both spouses 65 or older: extra $3,300 total
That stacks on top of the basic 2026 standard deduction of $16,100 for single filers, $24,150 for head of household, and $32,200 for married filing jointly.2Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 A married couple where both spouses are 65 starts with a combined $35,500 of tax-free income. Claiming it is simple: check the age box on line 12d of Form 1040 or 1040-SR and the form does the math.3Internal Revenue Service. Instructions for Form 1040
The New $6,000 Enhanced Senior Deduction
A separate deduction, enacted as part of the One, Big, Beautiful Bill, is available for tax years 2025 through 2028. Qualifying seniors can deduct up to $6,000 per person, or $12,000 for a married couple filing jointly if both spouses are eligible.4Internal Revenue Service. Publication 554, Tax Guide for Seniors
Two features make this one worth paying attention to. First, it phases out at higher incomes: modified adjusted gross income above $75,000 (single) or $150,000 (joint) begins to reduce it. Second, you can claim it whether you take the standard deduction or itemize.
Stack everything together and the ceiling for tax-free income is substantial. A single 65-year-old could shelter up to $24,150 in 2026 ($16,100 basic + $2,050 age addition + $6,000 enhanced). A married couple where both spouses are 65 could shelter up to $47,500. For many retirees living mainly on Social Security and a modest pension, that eliminates federal income tax entirely.
Social Security May Become Taxable
Many people are surprised that Social Security benefits can be taxed. Whether yours are depends on your combined income, which the IRS calculates by adding your adjusted gross income, any tax-exempt interest, and half of your Social Security benefits for the year.5Social Security Administration. Must I Pay Taxes on Social Security Benefits?
- Up to 50% of benefits become taxable when combined income exceeds $25,000 (single) or $32,000 (joint).
- Up to 85% of benefits become taxable when combined income exceeds $34,000 (single) or $44,000 (joint).
Congress set these thresholds in 1983 and 1993 and has never adjusted them for inflation.6Office of the Law Revision Counsel. 26 USC 86 – Social Security and Tier 1 Railroad Retirement Benefits That is why more retirees cross them every year. Consider a single filer receiving $22,000 in Social Security and earning $15,000 from a part-time job: combined income is $15,000 plus $11,000 (half of the benefits), or $26,000, which sits just above the $25,000 line. Some benefits are now taxable. Withdrawals from traditional IRAs and 401(k) accounts count toward adjusted gross income too, which is a common way retirees drift into the 85% bracket without realizing it.
When You No Longer Have to File
Because the standard deduction is larger at 65, the income level below which you don’t need to file a federal return is also higher. For 2026, based on the standard deduction, the thresholds are roughly:
- Single, 65 or older: $18,150
- Head of household, 65 or older: $26,200
- Married filing jointly, one spouse 65 or older: $33,850
- Married filing jointly, both spouses 65 or older: $35,500
Below these marks, you generally don’t owe a return.4Internal Revenue Service. Publication 554, Tax Guide for Seniors Not having to file isn’t the same as shouldn’t file, though. If a pension or part-time employer withheld federal tax, filing is the only way to get it back. Refundable credits work the same way.
Skipping a return when you do owe brings a failure-to-file penalty of 5% of the unpaid tax per month, up to 25%.7Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax If the return is more than 60 days late, the minimum penalty is $485 or 100% of the unpaid tax, whichever is less.
Medicare Premiums Are Deductible
Enrolling in Medicare creates new premium costs, and those premiums count as deductible medical expenses. That includes Part B, Part D prescription drug plans, Medigap supplemental policies, and Part A if you have to pay for it out of pocket rather than receiving it free.8Internal Revenue Service. Publication 502 (2025), Medical and Dental Expenses
If you itemize on Schedule A, you can deduct medical and dental expenses that exceed 7.5% of your adjusted gross income. Only the amount above that floor counts. With adjusted gross income of $50,000, you would need more than $3,750 in total medical costs before any of it becomes deductible. Premiums, copays, dental work, prescriptions, and hearing aids all count toward the total.
Self-employed retirees get a better deal. Medicare premiums qualify for the self-employed health insurance deduction, which reduces adjusted gross income directly rather than requiring you to itemize.9Office of the Law Revision Counsel. 26 USC 162 – Trade or Business Expenses You claim it on Schedule 1, the 7.5% floor doesn’t apply, and lowering AGI can also help you qualify for other credits and deductions.
Higher-income retirees pay more for Medicare through the Income-Related Monthly Adjustment Amount (IRMAA), which is based on your modified adjusted gross income from two years earlier. For 2026, the standard Part B premium is $202.90 per month; surcharges start once income crosses $109,000 (individual) or $218,000 (joint) and can push the total to $689.90 per month.10Centers for Medicare & Medicaid Services. 2026 Medicare Parts A and B Premiums and Deductibles The full premium, IRMAA surcharge included, is deductible.
Your HSA Contributions Have to Stop
If you have been contributing to a Health Savings Account through a high-deductible health plan, Medicare enrollment ends that. Starting with the first month you are enrolled in any part of Medicare, your HSA contribution limit is zero.11Internal Revenue Service. Publication 969 (2025), Health Savings Accounts and Other Tax-Favored Health Plans Existing HSA funds are still yours to spend tax-free on qualified medical costs, including Medicare premiums and copays. You just can’t add to the account.
In the year you turn 65, the contribution is prorated for the months you were eligible before Medicare began. For 2026, the self-only HSA limit is $4,400 and the family limit is $8,750, plus a $1,000 catch-up if you are 55 or older.12Internal Revenue Service. Notice 26-05
One trap: when you first enroll, Medicare Part A can be backdated up to six months. Any HSA contributions made during that retroactive window are excess contributions and may draw a 6% penalty tax for each year the excess stays in the account. If you plan to delay Medicare while you keep contributing, stop your HSA contributions early enough to avoid the overlap.
The Credit for the Elderly or the Disabled
A separate federal credit exists for people 65 and older, worth 15% of a base amount ($5,000 single, $7,500 joint if both qualify) after two reductions.13Office of the Law Revision Counsel. 26 USC 22 – Credit for the Elderly and the Permanently and Totally Disabled The base is reduced by any nontaxable Social Security or pension benefits and by half of the amount your adjusted gross income exceeds $7,500 (single) or $10,000 (joint). Because Social Security payments alone often exceed the base, the credit phases out for most retirees. A single filer’s credit disappears once adjusted gross income reaches $17,500 or nontaxable Social Security hits $5,000. Still, if your income is very modest, it is worth running the numbers on Schedule R. The IRS will calculate it for you if you check the box in Part I and write “CFE” on Schedule 3, line 6d.14Internal Revenue Service. Instructions for Schedule R (Form 1040)
Withholding and Estimated Payments Change
Working paychecks handled tax withholding automatically. Retirement income does not, at least not without your input. Pension income may or may not have withholding set up, Social Security withholds only if you request it using Form W-4V, and investment income has no withholding at all. If total withholding falls short of what you owe, the IRS expects quarterly estimated payments.15Internal Revenue Service. About Form 1040-ES, Estimated Tax for Individuals The deadlines are April 15, June 15, September 15, and January 15 of the following year. Many retirees prefer to set voluntary withholding on Social Security (W-4V) and pension payments (W-4P) instead of writing checks four times a year.
Form 1040-SR Is an Option
Once you are 65, you can file using Form 1040-SR. It is functionally identical to Form 1040, with the same lines and schedules, but uses larger text and includes a standard deduction chart on the last page that accounts for the age-related increases.4Internal Revenue Service. Publication 554, Tax Guide for Seniors It won’t change what you owe, but it makes reading the numbers easier and cuts the chance of a checkbox error.