Health plans love to throw numbers at you: 80/20, 70/30, deductibles, out-of-pocket maximums. Most people nod, pick based on the premium, and hope for the best. But that little fraction — the coinsurance split — quietly decides how much you pay when you actually use care, and the difference between an 80/20 and a 70/30 plan can be thousands of dollars in a bad year. Let’s translate what those numbers really mean for your wallet.

What the numbers actually mean

The split is your coinsurance — how you and the insurer share costs after you’ve met your deductible. On an 80/20 plan, once your deductible is met, the insurer pays 80% of covered costs and you pay 20%. On a 70/30 plan, the insurer pays 70% and you pay 30%. That extra 10 percentage points on your side might sound small, but on big medical bills it adds up fast.

How it fits with your deductible and out-of-pocket max

Coinsurance doesn’t work alone. First you pay your deductible (the amount before the insurer chips in). Then coinsurance kicks in — you pay your share (20% or 30%) of covered costs. That continues until you hit your out-of-pocket maximum, after which the insurer pays 100%. So the 70/30 vs 80/20 difference matters most in the zone between your deductible and your out-of-pocket max — which is exactly where a serious illness or surgery lands you.

A worked example

Say you have a $3,000 deductible and a covered procedure with $20,000 in bills after the deductible is met. On an 80/20 plan, you’d owe 20% of that — $4,000 — plus your deductible, before any out-of-pocket cap. On a 70/30 plan, you’d owe 30% — $6,000 — plus your deductible. That’s a $2,000 swing on a single event, purely from the coinsurance split. Your out-of-pocket maximum caps the total, but on a 70/30 plan you typically hit higher costs faster, and the cap itself is often higher too.

Why the “cheaper” plan can cost more

Here’s the trap. A 70/30 plan usually advertises a lower monthly premium, so it looks like the budget-friendly choice. But you’re trading a smaller monthly bill for a bigger bill when you need care. If you stay healthy all year, you might come out ahead. If you have one significant medical event, that 30% share can erase your premium savings several times over. The cheapest premium and the cheapest year are often not the same plan.

So which should you choose?

It depends on the trade you want to make. If you rarely use care and want the lowest monthly cost — and you have savings to absorb a bad year — a 70/30 plan with a lower premium can make sense. If you want more protection when something big happens, or you use care regularly, an 80/20 plan usually costs less overall despite the higher premium. The key is to compare total potential cost — premium plus deductible plus your coinsurance share up to the out-of-pocket max — not just the sticker premium.

What to actually compare

• Monthly premium — what you pay no matter what.
• Deductible — what you pay before coinsurance starts.
• Coinsurance split — your share after the deductible (the 20% or 30%).
• Out-of-pocket maximum — your worst-case total for the year.
• Network — whether your doctors are covered, which affects all of the above.

Two people, two right answers

Consider two neighbors. The first is single, healthy, rarely sees a doctor, and has a solid emergency fund. For them, a 70/30 plan with a low premium often wins — they pocket the monthly savings and could comfortably absorb a rare bad year. The second is managing an ongoing condition and sees specialists regularly. For them, the higher premium of an 80/20 plan is almost always worth it, because they’ll spend enough time in the post-deductible zone that paying 20% instead of 30% saves them far more than the premium difference. Same two plans, opposite right answers — because the “best” split is entirely about how much care you actually use. There is no universally better number; there’s only the better fit for your life.

This is also why shopping on premium alone is so risky. The premium is the one number plans advertise loudest, precisely because it’s the easiest to make look attractive. The coinsurance split, the deductible, and the out-of-pocket maximum are where the real cost of a tough year hides — and where a few minutes of comparison can save you thousands.

Where private insurance fits in

Here’s the advantage most people don’t realize: on the marketplace you pick from fixed boxes, but with private insurance you can build your own coverage and decide your benefits — including how you balance premium against coinsurance and deductible. This is what I do. I work with private health insurance, and in 2026 more people are going private because, if you don’t qualify for subsidies, it’s most of the time actually cheaper — and it still offers PPO plans that are getting hard to find on the marketplace, where networks keep narrowing and deductibles and out-of-pocket maximums keep climbing. Instead of guessing between two preset splits, we design the structure that fits how you actually use care.

Common questions

Is 80/20 always better? No — it usually costs more monthly. It’s “better” only if the lower costs-when-you-use-care outweigh the higher premium for your situation.

Does coinsurance apply before or after the deductible? After. You pay the deductible first, then your coinsurance share until you reach the out-of-pocket maximum.

The bottom line

The 70/30 vs 80/20 split isn’t a technicality — it’s a real decision about how much risk you keep versus how much you pay every month. Compare total potential cost, not just the premium, and choose the split that fits how you actually use care. Let’s run your numbers and pick the structure that costs you the least in the year that matters.

Confused by the numbers on your plan? Let’s decode them together — book a free review.