Accounts and taxes

Open Enrollment: A Worksheet, Not a Guess

A worksheet method for open enrollment - last year's usage as the base, three totals per plan, and the network and formulary checks that decide it.

Current as of August 31, 2026 Accounts and taxes

Most people pick a health plan by premium and vibes. The premium is one number out of four, and the vibes are marketing. An hour with last year’s claims and a simple worksheet gets you an answer you can defend. Here is the method.

Step 1: Pull last year’s actual usage

Your best estimate of next year is last year, adjusted for anything you already know is coming.

Log into your current insurer’s portal and export or list every claim from the last 12 months. Each EOB shows the allowed amount - the negotiated price, not the billed price - and what you paid. You want three tallies:

Visit counts by type: primary care, specialist, urgent care, therapy, labs, imaging.
Prescriptions: each drug, dosage, and how many fills per year.
Total allowed amounts: what your care actually cost at negotiated rates.

Then adjust for known changes: a planned procedure, a pregnancy, a kid aging into orthodontia, a prescription you started in November that will now run all 12 months. You are not predicting the unpredictable. You are refusing to ignore the predictable.

Step 2: Compute three totals per plan

For every plan you are considering, compute these. The definitions of deductible, copay, and coinsurance are covered here if you need them.

Best case = premium x 12. This is what you pay if you use nothing. It is the only number the enrollment brochure puts in large type.

Expected case = premium x 12 + your estimated cost sharing. Walk last year’s usage through this plan’s rules: copays times visit counts, drug tiers times fill counts, and the deductible and coinsurance applied to anything that is not copay-based. It does not need to be exact. Being within a few hundred dollars beats guessing by thousands.

Worst case = premium x 12 + the out-of-pocket maximum. This is your exposure if the year goes badly. It is the number that matters most and appears in the smallest print. Our out-of-pocket calculator runs this math for you.

A worked example

A family used about $6,000 in allowed amounts last year: 10 office visits, two ER-free urgent care trips, routine labs, and two maintenance prescriptions. Their employer offers two plans.

	Plan A	Plan B
Monthly premium	$190	$410
Deductible	$3,300 (family)	$1,000 (family)
Coinsurance after deductible	20%	20%
Out-of-pocket maximum	$7,000	$4,500
Best case (premium x 12)	$2,280	$4,920
Expected case	$2,280 + $3,840 = $6,120	$4,920 + $2,000 = $6,920
Worst case	$2,280 + $7,000 = $9,280	$4,920 + $4,500 = $9,420

For this family, at this usage level, the totals land close together - which is itself useful information, because it means the decision can ride on the tiebreakers below rather than on price. A family expecting a $30,000 year would look hard at the worst-case row instead. Your numbers will differ. That is the point of doing your numbers.

One warning on the expected case: cost sharing routinely adds more than people expect, sometimes more than the premium itself. If your expected-case math surprises you, that is the worksheet working.

Step 3: Check your actual doctors against each network

A cheaper plan that excludes your doctors is not cheaper. For each plan finalist:

List every provider your household saw last year, plus your preferred hospital.
Search each one in that specific plan’s directory - the plan and network name exactly as listed in the enrollment materials, not just the insurer’s brand name. One insurer can run a dozen networks.
For anyone you cannot afford to lose, call the provider’s office and ask which networks they will participate in next year. Directories go stale; offices know their own contracts.

What in-network versus out-of-network does to your costs is large enough that this step can overrule everything in Step 2.

Step 4: Check your drugs against each formulary

Every plan publishes a formulary - the list of covered drugs and their tiers. Look up each prescription from Step 1:

Is it covered at all?
What tier, and what does that tier cost under this plan?
Any prior authorization or step therapy flags?

A maintenance drug sitting on tier 3 of one plan and tier 1 of another can move the expected-case math by hundreds of dollars a year. Five minutes per drug.

Step 5: The HSA tiebreaker

If the totals are close, check whether one plan is HSA-eligible. Per IRS rules, contributing to an HSA requires coverage under a qualifying high-deductible health plan and no other disqualifying coverage. For 2026 the contribution limits are $4,400 for self-only coverage and $8,750 for family coverage, plus $1,000 catch-up at age 55 or older.

An HSA is triple tax-advantaged: pre-tax in, untaxed growth, untaxed out for qualified medical expenses. If your employer seeds the account, count that as a direct reduction in the plan’s expected-case total. The full comparison of HSA, FSA, and HRA accounts is its own guide.

What the worksheet cannot do

It cannot predict an accident or a new diagnosis. That is what the worst-case row is for: it bounds the damage. You are choosing which shape of risk you prefer - lower fixed cost with higher exposure, or higher fixed cost with lower exposure - with real numbers attached to each.

Keep the worksheet. Next year’s open enrollment starts with this year’s claims, and the second pass takes half the time. A tracker makes the claims tally trivial, and prices for the procedures you might be estimating are covered in what things actually cost.

Sources

Figures and rules on this page are current as of August 31, 2026. Dollar limits and deadlines change - check the linked source before you rely on a number.

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