HDHP vs. conventional health plan: How to determine the best fit

For Themistocles, this means that the HDHP turns out to be an even better deal; instead of saving just $458, Themistocles is now looking at a post-tax savings of as much as $1,765.

Granted, the tax-advantaged Bogleheads strategy is only useful for those who know ahead of time that they are going to incur high medical expenses. For those with high ongoing medical expenses, an HDHP becomes a better deal as their tax bracket climbs higher. 

In short, if an unhealthy individual opts for an HDHP, hitting their deductible annually, the tax savings offered by an HSA — in combination with an HDHP's low premiums but capped liability — makes for significant savings.

Low Premiums + Capped Liability + Tax Deduction = Great Savings

Consider the matrix below for deliberation on opting for an HDHP.

In the middle

Individuals with moderate ongoing medical expenses may be best served by electing a conventional plan. With an HDHP, the individual may pay many costs out-of-pocket without ever reaching the deductible (the point at which the HDHP begins paying benefits). Consider a second example:

Darius must see a chiropractor every month for a treatment costing $335 per visit ($4,020 annually), which Darius would have to pay out-of-pocket were he to elect an HDHP. (The chiropractor's treatment does not qualify as preventive). Though the expense of the chiropractor visits add up, the total out-of-pocket is not enough to get Darius to the top of his deductible.

Were Darius to elect a conventional health plan, he would only be liable for a $40 copay for each visit ($480 annually). However, Darius would be liable for higher monthly premiums, higher than those premiums charged by an HDHP.

With such a narrow margin between the sum of all out-of-pocket expenses and the HDHP's deductible, the tax deduction offered by HSA contributions plays an important role in determining which health plan is the superior choice. When in a low (10%) tax bracket, the HDHP proves the inferior choice.

In a higher tax bracket, an HDHP proves a wise move:

However, if out-of-pocket expenses rise far above the amount that can be deducted for HSA contributions (i.e. $3,300 for individuals for 2014), then the conventional plan — with its high premiums but low co-pays — wins out. For the Darius example, assume that instead of $335 per visit, the chiropractor's fee was $500 per visit.

Takeaway

The matrix below summarizes the article:

The individual in the high tax bracket and in poor health (dark green box), has the greatest potential to benefit by utilizing an HDHP. Not only will the individual be paying low premiums for a defined out-of-pocket maximum, but he or she will benefit greatly by paying for those expenses with severely discounted after-tax dollars.

The individual with moderate health issues (yellow and red boxes) will need to decide if the tax benefits offered by an HSA will balance the out-of-pocket expenses required in a HDHP. This may be the case if the individual is in a high tax bracket (yellow box), with the out-of-pocket expenses hovering near the maximum allowable contribution ($3,300 for individuals). While the out-of-pocket expenses may be high, the combination of the low premiums and the tax savings from HSA contributions may render the HDHP election worthwhile. However, the individual in a low tax bracket with moderate health expenses (red box) should opt for a conventional plan, and not an HDHP.

Individuals in good health (top row, light green boxes) will pay smaller premiums and few (if any) out-of-pocket expenses. Those individuals in good health are less able to take advantage of the tax-savings offered to the degree that an individual in poor health can.

An individual in poor health in a low tax bracket (lower left) will have their out-of-pocket expenses capped annually. Though still a good fit, this low-tax-bracket-individual will not be able to generate as much tax savings as an individual in a high tax bracket.