Open Enrollment & Year End: Why Now Is the Best Time to Maximize Your HSA

By Matthew Gorrell, AFC®, ChFC® · 5 min read

Open enrollment season hits at the same time many people are thinking about year-end taxes, budgeting, and next year's financial goals. One tool becomes especially powerful during this window: the Health Savings Account (HSA). It may be one of the most tax-efficient accounts you'll ever use.

And if you're a high-earning professional, a growing family, or someone preparing for long-term investing, understanding how HSAs really work can help you keep far more of your money.

What Exactly Is an HSA?

A Health Savings Account is a tax-advantaged savings and investment account for people enrolled in a qualified high-deductible health plan (HDHP). To contribute to an HSA, you must:

• Be covered by an HSA-eligible HDHP
• Have no other disqualifying health coverage
• Not be enrolled in any part of Medicare
• Not be claimed as a dependent on someone else's tax return

Starting in 2026, bronze and catastrophic plans bought through the health insurance marketplace also count as HSA-eligible, which opens the door for many self-employed people and early retirees.

Unlike a Flexible Spending Account (FSA), your HSA money belongs to you, not your employer. It rolls over every year, you can invest the balance once it's high enough, and you keep it through job changes, retirement, or periods of unemployment.

2026 HSA Limits

• Contribution limit: $4,400 individual / $8,750 family
• Catch-up (age 55+): an extra $1,000
• HDHP minimum deductible: $1,700 individual / $3,400 family
• HDHP maximum out-of-pocket: $8,500 individual / $17,000 family

The contribution limits apply whether the money comes from you, your employer, or both combined. The IRS sets new limits each year, so check the current numbers when you plan next year's contributions.

The Last-Month Rule

If you are HSA-eligible on December 1, the IRS lets you contribute the full year's limit, even if you were eligible for only one month. Someone who switches to an HSA-eligible plan and is covered by December 1, 2026 could contribute up to $4,400 (individual) or $8,750 (family) for 2026, plus the $1,000 catch-up at age 55 or older.

But there's a catch

You must stay HSA-eligible through December 31 of the following year, a period called the “testing period.” If you lose eligibility early (a job change, switching insurance, enrolling in Medicare), the extra contribution becomes taxable income and may carry a 10% additional tax.

This rule is powerful, but it should be used intentionally and with awareness of life changes on the horizon.

The Triple-Tax Advantage

No other account in the U.S. tax code offers this combination:

1. Tax-deductible contributions (or pre-tax through payroll)
2. Tax-free growth on interest, dividends, and capital gains
3. Tax-free withdrawals for qualified medical expenses

You won't find this combination in a Roth IRA, traditional IRA, brokerage account, or 401(k).

An HSA can be both a healthcare safety net and a stealth retirement account.

Advantages of Your First Year in an HSA

1. Lower monthly premiums

HDHPs usually have lower monthly premiums. For healthy households or people with predictable medical usage, the savings can be substantial and free up cash for the HSA itself.

2. Rollover and portability

FSAs are generally “use it or lose it.” HSAs are yours to keep. If you change employers, switch insurance, or retire, the money stays with you.

3. The opportunity to invest

Many HSA providers let you invest once your cash balance passes a threshold, often $1,000 to $2,000. After that, contributions can go into index funds, mutual funds, or ETFs. This can turn your HSA from a medical fund into a long-term wealth-building account.

4. No required minimum distributions

Unlike traditional IRAs and 401(k)s, HSAs have no required minimum distributions. You can let the money grow for as long as you want, which gives HSAs a unique planning edge for retirement.

Disadvantages and Risks to Consider

HSAs aren't the right choice for every household, especially in year one.

• Higher deductibles: You pay more out of pocket before insurance kicks in. If you expect major medical expenses (pregnancy, surgery, chronic needs), be ready for higher upfront costs.
• You need cash flow: If you don't want to touch your HSA for small bills, you'll need cash to pay them out of pocket.
• More recordkeeping: If you plan to reimburse yourself years later, you must keep receipts and documentation organized.
• Not ideal for everyone: People with recurring expensive medical needs may be better off with a lower-deductible plan, even without HSA eligibility.

Smart Year-End HSA Strategies

1. Treat your HSA like a long-term investment account

If you're healthy and your cash flow is stable, consider contributing up to the full limit, paying medical costs out of pocket, and letting the HSA grow untouched. Think of it as a tax-free growth portfolio you tap only when needed.

2. Save your receipts, potentially for years

One of the most valuable but underused strategies: pay cash now, save your receipts, and reimburse yourself tax-free later. There's no time limit on reimbursement, as long as the expense was incurred after you opened the HSA. A $2,000 medical bill this year could be reimbursed tax-free a decade from now, after ten years of tax-free growth on that money. Just keep digital copies of receipts in a secure folder.

3. Invest once you cross your provider's minimum

Once you pass the cash threshold, shift new contributions into low-cost diversified funds and let time and compound growth do the work.

4. Use the last-month rule carefully

It's a powerful way to catch up on HSA funding, especially for high earners who switch to an HDHP at open enrollment. It's not a good fit for anyone planning to switch jobs, drop the HDHP mid-year, or enroll in Medicare during the testing period.

5. After Medicare: use your HSA for premiums

Once you enroll in any part of Medicare, you must stop contributing, but your HSA stays valuable. Once you're 65 or older, you can use it tax-free for Medicare Part B, Part D, and Medicare Advantage premiums, qualified long-term care insurance premiums (up to IRS limits), and deductibles, copays, and coinsurance. You cannot use it tax-free for Medigap (Medicare Supplement) premiums.

Case Study: Using an HSA as a Wealth Engine

Consider a family in their early 40s, healthy, with predictable medical costs. During open enrollment they switch to an HDHP. They contribute the full family limit each year, pay small medical bills out of pocket, save their receipts, and invest the HSA for growth.

By age 65, if they keep contributing the maximum and invest for growth, their HSA could reach several hundred thousand dollars, depending on market returns. That money has grown tax-free, has no required minimum distributions, can be used tax-free for medical expenses, and can be used for anything after 65, taxed like a traditional IRA withdrawal.

Few other accounts offer that level of flexibility.