Key takeaways
- HSA rules forbid pairing with a general-purpose FSA, so most HSA owners skip FSAs entirely and leave money behind.
- A limited-purpose version exists precisely for HSA holders, covering a narrower category of expense.
- Sizing the election conservatively is the whole discipline, since the coordination rules are otherwise simple.
To contribute to an HSA you must be covered by a qualified high-deductible plan and — the part that surprises people — by no disqualifying second coverage. A general-purpose health FSA counts as disqualifying, even a spouse’s. The limited-purpose FSA exists as the carve-out: restricted to dental and vision expenses, it sits alongside an HSA without breaking eligibility.
Why bother with both
Because the two accounts do different jobs. The LPFSA gives this year’s dental and vision costs — cleanings, orthodontia, glasses, contacts, LASIK — a pre-tax discount at your marginal rate. Every dental dollar the LPFSA absorbs is a dollar your HSA doesn’t spend, which matters most if you’re running the delayed-reimbursement strategy and want the HSA compounding untouched. Predictable expenses through the FSA; long-term compounding in the HSA.
Sizing the election
LPFSA money is generally use-it-or-lose-it on the plan’s calendar, so elect against known costs, not hopes: the family’s scheduled cleanings, the kid’s orthodontia year, the glasses prescription that always changes. Orthodontia deserves special attention — multi-year treatment plans interact with plan-year rules in ways worth confirming with your administrator before electing big.
The coordination details
Substantiation is stricter than with a general FSA — keep itemized statements showing the dental/vision nature of each expense. Some plans convert the LPFSA to post-deductible status mid-year (covering broader expenses once the health deductible is met); read yours. And re-run the math at every qualifying life event — the right election changes when the family does.
Educational only. This page is general information, not individualized investment, legal, or tax advice. Rules depend on your account type, transaction, tax year, and circumstances — consult a qualified professional.