When Can I Contribute to a Health Savings Account?

A Health Savings Account (HSA) is a savings account with tax advantages for qualified medical costs. Contributions can lower your taxable income, grow tax-free, and be withdrawn tax-free for eligible expenses. Understanding when you can contribute is governed by Internal Revenue Service (IRS) rules covering your health plan, contribution deadlines, and how life changes affect your limits.

Core Eligibility for Making Contributions

To contribute to an HSA, you must be covered by a high-deductible health plan (HDHP) on the first day of a month. For 2025, the IRS defines an HDHP as a plan with a minimum annual deductible of $1,650 for self-only coverage or $3,300 for family coverage. These plans also have a maximum out-of-pocket expense limit of $8,300 for self-only coverage or $16,600 for family coverage.

In addition to having an HDHP, you cannot have other health coverage that is not an HDHP, such as a spouse’s non-HDHP plan or a general-purpose Flexible Spending Account (FSA). Certain types of coverage are permitted, however, including dental, vision, disability, and long-term care insurance.

You are also ineligible to contribute if you are enrolled in any part of Medicare. This restriction applies regardless of age and ceases your ability to make new contributions upon enrollment. Finally, you cannot be claimed as a dependent on another person’s tax return for the year you wish to make contributions.

Contribution Deadlines and Timing

You can make HSA contributions for a tax year at any point from January 1 of that year until the federal income tax filing deadline, which is around April 15 of the following year. This deadline is firm and does not extend even if you file for an extension on your tax return. For example, contributions for the 2024 tax year can be made until April 15, 2025.

This flexibility allows you to assess your finances after the year has ended and still make contributions to reduce the prior year’s taxable income. When making a contribution between January 1 and the tax deadline, you must inform your HSA administrator whether the funds apply to the current or prior year. This ensures the contribution is correctly reported on IRS Form 8889.

Calculating Your Annual Contribution Limit

The IRS sets annual contribution limits. For 2025, the maximum contribution is $4,300 for individuals with self-only HDHP coverage and $8,550 for those with family HDHP coverage.

Individuals age 55 or older by the end of the tax year can make an additional “catch-up” contribution of $1,000 annually. If both you and your spouse are 55 or older with separate HSAs, you must each make the catch-up contribution to your own account.

If you are eligible for only part of the year, your limit is prorated based on the number of eligible months. For instance, if you had self-only coverage and were eligible for five months in 2025, your prorated limit would be 5/12 of $4,300, or $1,791.67.

An exception to this is the “last-month rule.” If you are eligible on the first day of the last month of the tax year (December 1), you can contribute the full maximum for that year. This rule requires a “testing period” where you must remain HSA-eligible for the entire following calendar year. Failing this testing period makes the extra contributions taxable income and subject to a 10% penalty.

How Life Changes Affect Your Contributions

Life events can alter your contribution ability or limit during the year. If you lose HDHP coverage or gain other disqualifying health coverage, your eligibility ends, and your contribution limit for that year must be prorated based on the number of eligible months.

Employer contributions also impact your personal limit. Any amount your employer contributes to your HSA counts toward your annual maximum. For example, if you have family coverage in 2025 with an $8,550 limit and your employer contributes $1,500, your personal contribution limit is reduced to $7,050.

Changes in family structure, like marriage or divorce, can also adjust your limit. Switching from self-only to family HDHP coverage increases your contribution limit for the months you have family coverage. A divorce could change your status from family to self-only, requiring a recalculation of your prorated limit. A court-ordered transfer of HSA assets during a divorce is a non-taxable event.