Dental Practice Debt-to-Income Ratios: The Real Numbers

A dentist who buys an $850,000 practice this year, carries the average school balance on top of it, and then does absolutely nothing wrong can be earning less than a salaried associate by the fourth year. Not because production fell, not because a hygienist quit, but because the loan payment is the only line on the P&L that never has a bad year.

That is the case we want to make, and it cuts against how nearly every practice purchase in this country gets underwritten. Our view: debt-to-income is the wrong test. It measures a stock against a flow, it flatters buyers who have income and punishes ones who have margin, and it tells you nothing about the only question that matters, which is whether your practice can produce the cash to make a fixed payment in a year when collections stall and costs don't. The number to underwrite against is annual debt service as a share of collections. We'd refuse any deal that pushes that above 12%, and we'd walk away from anything north of 15% no matter how good the chair count looks.

Why $1.15 Million of Debt Isn't the Real Problem

Start with the raw load. The American Student Dental Association puts average dental school debt at $297,800 per graduate. Add a typical single-location acquisition note of $850,000 and you're at roughly $1.15 million before you've bought a scanner.

Now the income side. The Bureau of Labor Statistics reports median annual wages for dentists of $176,110 as of May 2025. The ADA Health Policy Institute puts average general-practice dentist income at $215,320 in 2025. Run the ratio a lender would run and you get somewhere between 5.3x and 6.5x debt to income, which sounds catastrophic and is, in practice, survivable. Plenty of owners carry it and sleep fine.

That is exactly why the ratio is useless. It doesn't distinguish between a $297,800 federal balance on a 20 or 25-year schedule with income-driven options and a $850,000 bank note with a 10-year term and your house behind it. Those two liabilities look identical to a spreadsheet and behave nothing alike. One flexes. The other doesn't. A multiple of income can't see the difference, and the difference is everything.

The second problem with income-based ratios is that they use the wrong denominator. Your income is the residual after overhead. It is the most volatile number in the business and the one you have the least direct control over in any single year. Collections are the number you can forecast. Fixed debt service divided by collections is a test you can actually pass or fail in advance.

The Five-Year Squeeze That Costs This Owner $66,205

Take a practice collecting $900,000 with overhead at 62%. That's $558,000 of expenses and $342,000 of earnings before any debt service.

Now layer the debt. The $297,800 school balance at 7% over 20 years costs about $2,309 a month, or $27,700 a year.

The $850,000 acquisition note at 8% over 10 years costs about $10,313 a month, or $123,760 a year.

Combined debt service is $151,460, which leaves the owner $190,540 pre-tax and puts debt service at 16.8% of collections.

On day one that is a good year. $190,540 beats the BLS median and sits below the ADA average, which is what most buyers expect while they're paying down a purchase. The deal closes. Everyone shakes hands.

Here is what happens next if nothing goes wrong. The ADA HPI trend over the trailing five years shows practice expenses rising 4.9% a year while revenue grows 1.4%. Apply those two rates and hold the loan payments flat, because loan payments are flat.

• Year 2: collections $912,600, expenses $585,342, earnings before debt $327,258, owner take-home $175,798.
• Year 3: collections $925,376, expenses $614,024, take-home $159,892.
• Year 4: collections $938,331, expenses $644,111, take-home $142,760.
• Year 5: collections $951,467, expenses $675,672, take-home $124,335.

Five years, no disasters, and take-home falls $66,205, a 35% cut.

By year 4 this owner is pre-tax below the $176,110 BLS median for a dentist with no loan guarantee, no landlord, no payroll, and no 6 a.m. equipment call. By year 5 they're 29% below it while personally guaranteeing $850,000.

None of this shows up in a debt-to-income ratio. On day one the ratio said 5.3x. On day one the ratio was fine. The ratio was fine the whole way down.

What Most Owners Get Wrong: Underwriting Against Income Instead of Collections

The specific mistake is treating the loan payment as a claim on income rather than a claim on collections, and it gets made hardest by two groups.

First, buyers three to six years out of school. They come out of residency or associateship with a clear picture of their W-2, they've been told the school debt is normal, and the broker's pro forma shows them clearing $190,000 in year one. They compare that number to their associate pay, see a raise, and sign. They never stress the expense line, because as associates they never had to look at an expense line. The pro forma's overhead percentage is a snapshot of the seller's last good year, and the seller had no acquisition debt.

Second, and this is the more expensive version, mid-career owners adding a second location or a big build-out. They already service a note comfortably, so they reason from the comfortable note. What they miss is that the first loan was underwritten against collections that have since drifted while overhead compounded. They stack new fixed debt onto a margin that is thinner than it was when they last measured it, usually three or four years earlier. Then both notes come due in the same slow quarter.

Both groups make the same error: they hold overhead constant in their heads. Every practice owner we've ever argued with about this says some version of "we'll manage the expense side." The HPI numbers say the profession as a whole has not managed it. Expenses up 4.9% a year against 1.4% revenue growth is not a story about bad operators. It's a story about supply costs, wages, and fee schedules that don't move. If you assume you'll beat that trend, fine, but don't finance the assumption.

The 12% Line, and Why We'd Walk at 15%

Our rule: total fixed annual debt service, education plus practice plus equipment, should not exceed 12% of collections at signing. Not 12% of income. 12% of collections.

Work the example backward. At $900,000 of collections, 12% gives you $108,000 of total annual debt service. The school loan takes $27,700 of that, leaving $80,300 for the practice note.

At 8% over 10 years, $80,300 a year supports about $551,500 of principal, not $850,000.

That is a purchase price near 61% of collections rather than 94%.

Owners will read that and say the market doesn't clear at 61% of collections, and in a lot of metros they're right. That is the point. The market price and the serviceable price have come apart, and when they come apart the buyer absorbs the gap out of take-home pay over ten years. We'd rather lose the deal than fund the gap. There is a version of this where you bring more cash to close, and that version we like. There is no version where a 16.8% debt-service load becomes safe because the practice is nice.

At 15% and above we don't negotiate, we leave. At that level a single bad year, one associate departure or one insurance plan renegotiation, moves you from thin to non-current, and non-current on a personally guaranteed note is a different kind of problem than a slow quarter.

Where Refinancing Helps and Where It Quietly Costs $224,568

The instinct when debt service runs hot is to refinance for a lower rate. Rate is usually the smaller lever. Term is the big one.

Stretch that same $850,000 at 8% from 10 years to 15 and the payment drops from $10,313 to about $8,123 a month, cutting annual debt service by $26,282 and pulling total debt service down to 13.9% of collections.

That $26,282 a year is real breathing room and it arrives immediately. It also costs $224,568 in additional interest over the life of the loan.

We think that's a trade worth making when the alternative is a covenant breach or a year of drawing nothing. We think it's a bad trade when it's used to justify a bigger purchase price at closing, which is how it usually gets used. Stretching term to survive is defensible. Stretching term to qualify is how owners end up in year nine of a fifteen-year note with a practice that needs $180,000 of new equipment.

One asymmetry worth respecting: federal education debt has repayment options that bend when income falls. Practice debt has none. If you're going to accelerate one of the two, the answer is almost never the school loan first, no matter how much the balance annoys you.

Do This Before Friday

Pull last twelve months of collections and total every fixed debt payment you make, education, practice, equipment, and any build-out note. Divide debt service by collections and write the percentage on one line. If it's above 12%, get a term-extension quote from your current lender this week and model what the payment does to your take-home, and if it's above 15%, treat that call as urgent rather than a project for the quarter. Then rerun the same division using collections at 1.4% growth and overhead at 4.9% growth for three years out, because that is the year the number actually has to survive.

If you want the overhead half of that equation checked against how other practices are structured before you call your lender, our overhead calculator will tell you where your expense load sits and how much margin is genuinely available for debt service. Run your own numbers and you'll know whether a term extension buys you room or just moves the problem five years out.

We're watching two things that would move the 12% line. If HPI expense growth decelerates below 3% a year for two consecutive reporting periods, the compounding squeeze weakens and a higher debt-service load becomes defensible. And if lenders start writing 20-year practice notes at competitive rates the way they do commercial real estate, the arithmetic changes again. Neither has happened yet. Until one does, assume your loan payment will be the most reliable number in your practice, and that reliability is not on your side.