Employers told Mercer this fall that their health benefit costs per employee will rise 8.2% in 2027, the biggest jump since 2003, and 59% of employers in its survey plan cost-cutting changes such as higher deductibles. So the benefits portal you open in the next few weeks will probably look worse than last year’s. The instinct, when deductibles climb, is to grab whichever plan still has the smallest one. In the HDHP vs PPO decision, that instinct is often the most expensive move on the menu, and you can check whether it is for your menu in about five minutes with a pen.
The deductible is the wrong number to compare
A deductible tells you when the plan starts paying. It doesn’t tell you what the year costs you. Two numbers do that: your share of the premium, which you pay no matter what, and the out-of-pocket maximum, which caps what you can pay for in-network care. HealthCare.gov’s definition is blunt about one detail people skip: premiums do not count toward the out-of-pocket maximum. Your real ceiling for the year is premiums plus that cap, minus any money your employer drops into a health savings account.
The premium half of that sum is big now. KFF’s 2025 Employer Health Benefits Survey put the average worker contribution at $1,440 a year for single coverage and $6,850 for family coverage. The average single deductible was $1,886, and a third of covered workers were already in a high-deductible plan with a savings account. When the premium you can’t avoid is often bigger than the deductible you might never reach, staring at the deductible means looking at the wrong column.
Most people pick a plan that loses no matter what happens
Economists have measured how often people get this wrong. In 2017 the Quarterly Journal of Economics published a study by Saurabh Bhargava, George Loewenstein and Justin Sydnor that looked at a large U.S. employer offering dozens of plan combinations. Some of those plans were “dominated,” meaning another option on the same menu cost less in every possible scenario, from zero doctor visits to a hospital stay. The researchers found that the majority of employees chose dominated plans, and the excess spending equaled 24% of the premiums they chose.
The people in that study had access to the same plan documents everyone gets. The low deductible felt safe, and paying an extra $100 a month to dodge a scary number in January reads like prudence. The portal never shows a “total cost if things go badly” column, so almost nobody builds one. Most open enrollment guides tell you to “think about how much care you use,” which is fine but skips the step that matters: first find out whether one plan wins in every year, healthy or not. If it does, your expected doctor visits don’t matter at all.
HDHP vs PPO in your worst year: the five-minute test
Take a realistic menu. Say your PPO costs you $150 a month, has a $1,000 deductible, 20% coinsurance, and a $4,000 out-of-pocket maximum. The HDHP costs $50 a month, has a $1,750 deductible (the IRS minimum for self-only coverage in 2027), the same 20% coinsurance, a $5,000 out-of-pocket maximum, and your employer puts $750 into your HSA.
Start with the worst year, the one where you hit the cap. On the PPO you pay $1,800 in premiums plus $4,000 in care, so $5,800. On the HDHP you pay $600 in premiums plus $5,000 in care, minus the $750 your employer gave you, so $4,850. The plan with the scarier deductible is $950 cheaper in the year everything goes wrong.
Now a quiet year with about $600 of care (preventive visits are covered before the deductible on both plans, so this is the extra stuff, a couple of sick visits and some labs). The PPO costs $1,800 plus $600, which is $2,400. The HDHP costs $600 plus $600 minus $750, so $450, and $150 is still sitting in your HSA. That gap is $1,950.
And the middle year, $3,000 in claims. On the PPO you pay the $1,000 deductible plus 20% of the remaining $2,000, so $1,400 in care and $3,200 total. On the HDHP you pay the $1,750 deductible plus 20% of the remaining $1,250, so $2,000 in care. Add $600 in premiums and subtract the $750 seed and you land at $1,850.
The shortcut is one comparison. Add the annual premium difference to the employer HSA contribution: $1,200 plus $750 is $1,950. Then subtract the smaller out-of-pocket maximum from the larger one: $5,000 minus $4,000 is $1,000. If the first number is bigger, the HDHP wins in every year for in-network care, and the PPO is a dominated plan. Your own menu might come out the other way, which is exactly why it’s worth the five minutes.
The HSA tax break is extra credit on top of the math
Every number above was calculated before taxes, so the HDHP won without any help from the IRS. The tax break is extra, and it’s sizable. Under Rev. Proc. 2026-24, you can put up to $4,500 into an HSA for self-only coverage in 2027 ($9,000 for family), with employer money counting toward the limit. Contributions made through payroll skip federal income tax and the 7.65% Social Security and Medicare tax. If you’re in the 22% bracket and contribute $3,000, that’s about $890 you keep (22% plus 7.65% is 29.65%, times $3,000). Most states add their own break on top, though a couple, including California and New Jersey, don’t.
A PPO person can get a similar tax break on medical spending through a flexible spending account, so the tax benefit shouldn’t be what tips you. The part an FSA can’t match is that HSA money rolls over and stays yours if you leave the job. That’s why we wrote about why swiping the HSA debit card can be the expensive move: once the account has a cushion, letting it grow and reimbursing yourself later is an option an FSA never gives you.
When the PPO really does win
The test cuts both ways, and I’d rather you trust it than trust me. Picture a different employer: PPO at $90 a month, HDHP at $50, no HSA seed, and a $2,500 gap between the out-of-pocket caps. The premium difference plus seed is $480, well under $2,500, so in a heavy year the PPO comes out ahead. If you’re planning a pregnancy, scheduling a surgery, or filling an expensive monthly prescription, run the middle-year math with your real numbers before assuming the HDHP wins.
Cash flow is the other honest objection. KFF found that only 3% of single workers in HSA-qualified plans had account contributions that met or exceeded their deductible. Lots of people pick the PPO because a $1,750 bill in February would hurt, even if they’d come out ahead by December. The fix is to put the monthly premium savings ($100 a month in the example) into your HSA from the first paycheck, and keep a small sinking fund for the gap until the account catches up. Also check the network. A cheaper plan that drops your doctor isn’t cheaper in the way you care about, and a family HDHP may have a deductible the whole household has to meet before coverage starts, which changes the middle-year math.
So before you click through open enrollment this year, write four numbers on a sticky note for each plan: annual premium, out-of-pocket maximum, employer HSA contribution, and whether your doctors are in network. Run the worst-year test. If one plan wins even when everything goes wrong, the HDHP vs PPO question is already answered, and you can spend the rest of the time figuring out where to put the money you just saved. This is general information, not personal financial or tax advice, so check your plan documents and talk to HR or a tax professional if your situation is complicated.