A dental membership plan pays for itself in under two months, on every honest count of what it costs — the number worth reading is the one that says the 25-month member life is still unproven

The moment

Two Rivers Dental has two offices in Springfield, Missouri — the same eleven people as the runway and hire-affordability stories: two dentists, three hygienists (soon four, part time), four assistants, two at the front desk.

About a fifth of the practice's patients, mostly at the newer second office, carry no dental insurance. Those patients skip the annual cleaning more often than anyone would like, because $225 out of pocket for a cleaning and exam is a number people postpone. In December 2025 the practice launched the Two Rivers Membership Plan: $29 a month, billed to a card on file, covering two cleanings, exams and bitewing X-rays a year plus 15% off any other treatment. No insurance company involved — the practice is both the seller and the payer.

It is October 2026. The plan has been running ten months. The two front-desk staff mention it to every patient without insurance at checkout and get a $10 incentive for every signup. Enough people have joined that the practice manager wants to know whether the plan is worth the ongoing effort, not whether it sounds like a good idea.

What they did instead

The practice manager's arithmetic, done once at launch and never revisited: the plan brings in $29 a month, the incentive to sign someone up is $10, and $10 against $29 looked obviously worth it. That comparison is not wrong. It is also not the question.

Nobody separated the $10 incentive from the rest of what a signup actually costs. The front-desk staff spend a few minutes explaining the plan to every uninsured patient at checkout, not just the ones who join — a pitch that doesn't close still costs the time it took. A one-time mailer to the practice's list of patients who hadn't been seen in over a year, sent the month the plan launched, was booked as a marketing expense and never divided by the signups it produced.

And nobody asked how long a member actually has to stay for $29 a month to be worth what it cost to sign them. Ten months of data is what the practice has. Ten months is also not very long.

The questions a CFO asks first

1. What does a member cost to sign up, once everything that goes into a signup is counted, not just the $10 incentive?
2. What does a member leave behind each month after the cost of the two visits and the materials?
3. How many months does that take to earn back what the signup cost?
4. How long does a member have to stay for the ratio of value to cost to mean anything, and how long has the plan actually been running?
5. Is the $10-per-signup figure the true cost of the next member, or does it get diluted by members who would have joined with no incentive at all?

Question 4 is the one the practice had never asked itself, because payback looked so fast that nobody thought to check what the fast number was resting on.

The arithmetic, shown

The plan's own figures. $29 a month per member. The two annual visits and materials cost the practice about $174 a year to deliver — $14.50 a month — leaving $14.50 of every member's $29 as contribution, a 50% margin. Of the members who have cancelled so far, the practice's own scheduling software puts monthly churn at 4%, which is what the ten months of data show.

**Scenario one — the incentive alone, which is the number everyone already uses.** CAC of $10, nothing else counted.

On this number, the plan looks close to free money. It is also missing most of what a signup costs.

Scenario two — the front-desk time and the mailer, added back. A pitch that doesn't close still takes the same few minutes as one that does; priced at the front desk's own hourly rate across everyone approached, that adds about $12 to every signup that succeeds. The launch mailer, divided by the signups it actually produced, adds another $5. Fully loaded: $27, not $10.

Still under two months. The $27 number changes how comfortable the plan looks — 8.39:1 is a different sentence than 22.64:1 — but it does not change the decision, because both clear the twelve-month bar by a wide margin.

**Scenario three — the number the practice would get by blending in the members who cost nothing.** Some patients ask to join during a routine exam, with no incentive paid and no mailer involved. Averaging those free signups in with the $27 marketed ones brings the blended figure down to $14 — a number that looks even better and answers a question nobody is asking.

$14 is true and useless for deciding whether to keep paying for the incentive and the mailer. The next member from that campaign costs $27, not $14, and $27 is the number that should decide whether the campaign keeps running — which, at 1.86 months' payback, it does.

What every scenario agrees on, and the one none of them can answer. The 25-month implied member life comes from ten months of churn data. No member of this plan has ever actually stayed 25 months, because the plan has not existed that long. The 24-month LTV figures above are the ones to trust more than the infinite-horizon ones for exactly that reason — they cover a period close to what has actually been observed — and even they assume the next fourteen months look like the first ten.

What changed

The practice kept running the incentive and the mailer. At $27 fully loaded and 1.86 months to pay back, the campaign clears the bar on the most demanding honest number available, not just the flattering one.

Two things stopped. The practice manager stopped quoting the $362.50 infinite-horizon lifetime figure when explaining the plan to the dentists — the 24-month figure of $226.41 is now the one on the one-page summary, because it doesn't rest on assuming years the plan hasn't lived through. And the blended $14 figure stopped being used to judge the marketing campaign, because the $27 fully-loaded number is the one that tells the practice what the next signup from that specific spend actually costs.

Nothing was decided about churn. The plan's first full year ends in December 2026, two months out, and the practice put a date on the calendar to look at whether members are actually renewing at that anniversary rather than carrying on with an assumption nobody has tested yet.

What the tool will not do

It will not tell the practice whether 4% monthly churn is the right number to plan on. That is only known by watching it hold over time, and ten months of a new plan is not that — the tool flags the mismatch between the assumed 25-month life and the 10 months actually observed, and stops there.

It will not decide whether the front-desk time spent on pitches that don't close is worth separating out as a cost, or whether the incentive should be higher or lower. Those are staffing and pricing questions the tool does not have the information to answer.

It will not average the fully-loaded and blended CAC figures into one number for the practice. It shows $27 and $14 side by side and says which question each one answers, because averaging them would quietly answer the wrong one.

It does not know that a member's 15% discount on other treatment reduces the margin on work the practice would otherwise have billed at full price. It prices only the two included visits, because that is the arithmetic it was given, and a member who uses the discount on a crown is a cost this figure does not see.

It does not say the plan is a good idea. It says a signup pays for itself in well under two months on every count tried here, and it says how much confidence that number deserves given how young the plan is. Those are two different sentences and the tool keeps them separate on purpose.