Health Insurance Explained: What You Actually Pay, and When

How health insurance works, in one paragraph: you pay a monthly premium to hold the policy. When you use care, you first pay the full negotiated price until you reach your deductible, then a percentage (coinsurance) of everything after that, until your spending hits the out-of-pocket maximum. From that point the plan pays 100% of covered in-network care until the plan year resets.

That is the whole machine. The confusion comes from the fact that health insurance is sold with five numbers and explained with none of them, and nobody shows you the arithmetic that connects them.

Here it is.

The five numbers that decide how health insurance works#

Think of it as two separate budgets. One is what you pay to have insurance. The other is what you pay to use it.

Premium is the first budget. It comes out every month whether you see a doctor or not. It is the only one of the five that you pay when nothing happens.

The other four are the second budget, and they fire in a specific order.

Deductible is what you pay yourself before the insurer starts splitting costs. A $3,000 deductible means the first $3,000 of covered care in the plan year is yours. Some services (an annual physical, most preventive screenings, often generic drugs) are covered before you hit it. Everything else waits.

Copay is a flat fee for a specific service. $35 to see your doctor, $20 for a generic prescription. Copays often apply immediately, deductible or not, which is why you can pay a copay in January and still owe the full deductible.

Coinsurance is your percentage after the deductible. At 20% coinsurance, a $10,000 procedure costs you $2,000 and the plan pays $8,000. It is the number people most consistently forget exists, and it is why "I met my deductible" does not mean "I am done paying."

Out-of-pocket maximum is the ceiling. Add up your deductible, copays and coinsurance for covered in-network care. When that total hits the maximum, the plan pays 100% for the rest of the year. Premiums never count toward it.

What does a bad year actually cost?#

Compare two plans the way an insurer does: total spend across the whole year, at several levels of use.

Plan A is the cheap-premium option. Plan B costs more monthly but protects you sooner.

Now run three years through it.

A healthy year. You see a doctor twice, get a flu shot, fill one prescription. Total medical spend: about $400. Plan A costs you $2,640 + $400 = $3,040. Plan B costs $4,920 + $400 = $5,320. Plan A wins by $2,280.

A moderate year. A minor injury, an urgent care visit, an MRI, physical therapy. Say $9,000 in billed care. Under Plan A you pay the $6,000 deductible, then 30% of the remaining $3,000 = $900, so $6,900 in care plus $2,640 in premiums = $9,540. Under Plan B you pay $1,500, then 20% of $7,500 = $1,500, so $3,000 in care plus $4,920 = $7,920. Plan B wins by $1,620.

A bad year. Surgery and a hospital stay: $85,000 billed. Both plans cap you at their out-of-pocket maximum. Plan A: $8,500 + $2,640 = $11,140. Plan B: $4,000 + $4,920 = $8,920. Plan B wins by $2,220.

The right question is not "which plan is cheapest." It is: what is the largest bill I could absorb without borrowing? Buy the plan whose out-of-pocket maximum sits at or below that number.

Why does staying in-network matter so much?#

Every insurer negotiates prices with a set of hospitals, doctors and labs. That set is the network. In-network, you pay the negotiated rate. Out-of-network, three bad things happen at once:

1. Your coinsurance percentage is worse, often 40–50% instead of 20%.
2. There is usually a separate, much higher out-of-network deductible and out-of-pocket maximum, and on many plans, no out-of-network maximum at all.
3. The provider can bill you the difference between what they charged and what your insurer considers reasonable. Federal No Surprises Act protections block this in the situations where you had no realistic choice.

That third one (balance billing) is the one that produces the horror stories. Federal law now blocks it in the situations where you had no realistic choice: emergency care, air ambulance, and out-of-network providers working at an in-network facility. That last case matters more than it sounds. It is why an in-network hospital could hand you an out-of-network anaesthesiologist's bill, and why it mostly cannot any more.

It does not protect you when you chose to go out-of-network.

Plan types in one paragraph each#

The four network models are covered in full in HMO vs. PPO vs. EPO vs. POS; the short version:

HMO. Cheapest premiums, narrowest network, no out-of-network coverage except emergencies. You pick a primary care doctor who refers you onward.

PPO. Most expensive, widest network, no referrals needed, and it pays something out-of-network. You are paying for flexibility.

EPO. A middle option: no referrals, decent network, but essentially no out-of-network coverage. Good if the network covers your doctors.

POS. An HMO that will pay something out-of-network if your primary care doctor refers you. Less common.

HDHP. Not a network type but a tax category, and the one place where how health insurance works starts interacting with your tax return. A plan qualifies as a high-deductible health plan only if it meets IRS minimums, which for 2026 are a deductible of at least $1,700 for self-only coverage or $3,400 for a family, with out-of-pocket maximums capped at $8,500 and $17,000. Meeting those tests is what makes you eligible to fund a Health Savings Account.

Item	2026 amount
HSA limit, self-only coverage	$4,400
HSA limit, family coverage	$8,750
HSA catch-up, age 55+Per person. Spouses each need their own HSA to both use it.	$1,000
Minimum HDHP deductible (self / family)Below this, the plan is not HSA-qualified no matter what HR calls it.	$1,700 / $3,400
Maximum HDHP out-of-pocket (self / family)	$8,500 / $17,000

The HSA is the reason a high-deductible plan can beat a richer plan even in a moderate year. Contributions are deductible going in, growth is untaxed, and withdrawals for medical costs are untaxed coming out. It is the only account in the U.S. tax code with all three.

Where does the money actually leak?#

Not knowing your plan resets. Deductibles and out-of-pocket maximums reset on the plan year, usually January 1. If you can control the timing of a procedure and you have already met your deductible, doing it in December instead of January can be worth thousands.

Paying the bill before the Explanation of Benefits. The EOB from your insurer is not a bill. It tells you what was billed, what the negotiated rate was, what the plan paid and what you owe. Provider bills routinely go out before or disagreeing with it. Never pay until you have compared the two.

Assuming prior authorisation means payment. It does not. Prior authorisation says the service is medically necessary. The claim can still be denied on a coding or coverage ground afterwards.

Missing the appeal window. A denied claim is not final. Insurers must give you an internal appeal and, if that fails, an external review by an independent party. Deadlines are short and unforgiving.

Letting a facility fee surprise you. A doctor's office owned by a hospital system can bill a separate facility fee for the same visit. Same doctor, same room, two charges.

How do you choose a plan in twenty minutes?#

That last point is the one that costs people a full year of the wrong coverage. Open enrolment windows move, and state-run exchanges set their own dates. Check the current window on HealthCare.gov or your state exchange rather than assuming last year's dates still hold.

The part nobody says out loud#

Health insurance is not a payment plan for medical care. It is protection against the tail: the 1-in-200 year that costs $200,000. Every plan design is a negotiation about how much of the small, likely costs you absorb in exchange for how much of the large, unlikely one the insurer absorbs.

Once you see it that way, the choice gets simpler. Do not optimise for the year where nothing happens. Optimise for the year where something does, and then check that the number you would owe in that year is a number you could actually pay.