Tax reserve calculator: How much of your practice profit belongs to the tax office?
Find out how much of your practice profit you need to set aside, calculated with the marginal tax burden, not the average rate. The calculation runs in your browser; your figures stay on your computer.
Free · Calculated under § 32a EStG · Your figures stay on your computer
Calculated under § 32a of the German Income Tax Act (EStG) and §§ 3 and 4 of the Solidarity Surcharge Act (SolzG) 1995 for the tax year 2026. The calculator models the tax rate schedule, not the determination of your taxable income: business expenses, provision expenses, allowances, the progression clause and the retention of profits under § 34a EStG are not taken into account. Not tax advice.
What the tax reserve calculator gives you
The rate that really counts
For the reserve on additional profit, what matters is not your average tax rate but the marginal tax burden: the share you give up from the next euro you earn. The calculator shows both and calculates with the right one.
The phase-in zone becomes visible
With the solidarity surcharge, there is a range in which every additional euro of income tax is charged at 11.9 instead of 5.5 percent. Your marginal tax burden there is higher than at a higher income. If you overlook this, you set aside too little.
Calculated by the law
The tax rate formula is taken unchanged from § 32a EStG (Income Tax Act), the exemption limit and cap of the solidarity surcharge from §§ 3 and 4 SolzG (Solidarity Surcharge Act). No rounded rules of thumb, no estimated brackets.
How to determine your reserve
Enter your profit
Enter your taxable practice profit, after operating expenses, before taxes. If you have other income, it goes in the second field.
Choose assessment and church tax
Assessed individually or jointly, and in which federal state you are liable for church tax. Both change the result noticeably.
Read off your reserve
You see the total amount, the share of profit and the monthly value. Plus the split into income tax, solidarity surcharge and church tax, the curve of your marginal tax burden and the result as a PDF.
Tax reserves in a medical practice: what matters
The most common back payment does not come from mistakes but from growth: profit rises, and the advance payments only follow with a delay. Planning with the average rate instead of the marginal tax burden amplifies the effect. Here is how to put it in context.
Why the average rate is misleading
If your average tax burden is 40 percent and you therefore set aside 40 percent of additional profit, you are setting aside too little. Additional profit is not taxed at the average but at the rate of the highest bracket reached. For a practice profit between €200,000 and €500,000, the two rates are around four to seven percentage points apart (single tax rate 2026 with solidarity surcharge); on €100,000 of additional profit, that is €4,000 to €7,000 missing in the spring.
The phase-in zone of the solidarity surcharge
The solidarity surcharge only becomes due when income tax exceeds an exemption limit. Directly above it there is no hard edge but a cap: the surcharge is at most 11.9 percent of the amount by which income tax exceeds the exemption limit. That sounds like relief, but it works the other way: in this range, every additional euro of income tax costs 11.9 instead of 5.5 percent surcharge. The marginal tax burden there is above that of incomes beyond the zone.
Why the burden does not rise evenly
The income tax schedule has five zones, the solidarity surcharge three ranges, and the boundaries do not coincide. The result is a curve with edges. If you interpolate linearly between two known points, you miss reality there: in the range of the phase-in zone, you are around five percentage points too low.
When you should set money aside
Income tax is paid in advance quarterly, on March 10, June 10, September 10 and December 10. The advance payments are based on the last assessment. If your profit grows, the advance payment initially remains too low; the difference comes all at once with the tax assessment notice. This is exactly what the monthly reserve is for.
What this calculator does not do
It models the tax rate schedule, not the determination of your taxable income. Operating expenses, depreciation, pension and insurance expenses, allowances, loss carryforwards, the progression clause and the retained-earnings relief under § 34a EStG are left out. That is enough for planning reserves; not for the tax return.
Frequently asked questions
What percentage of my practice profit should I set aside?
There is no universal percentage: it depends on the level of profit, the assessment and church tax liability. The calculator gives you the value for your situation. As an order of magnitude: with a profit in the mid six figures, the burden on additional profit is between 44 and 48 percent.
What is the difference between the average rate and the marginal tax burden?
The average rate is total tax divided by total income. The marginal tax burden is the share you give up from the next euro you earn. For the question of how much you need to set aside from additional profit, only the marginal tax burden matters.
What is the phase-in zone of the solidarity surcharge?
A range directly above the exemption limit in which the surcharge does not immediately apply at 5.5 percent but is capped at 11.9 percent of the amount above the exemption limit. This limits the absolute amount but increases the burden on every additional euro: in this zone, your marginal tax burden is higher than above it.
Does the calculator also work for a group practice?
Yes, provided you enter your share of the profit. In a group practice (Berufsausübungsgemeinschaft), profit is determined separately and allocated proportionally to the partners; it is then taxed personally for each partner. So enter your share, not the profit of the whole practice.
Are my entries secure?
Your figures stay on your device: the calculation runs entirely in the browser, and profit and income are not transmitted. Only the contact details you enter to unlock the full result are transmitted.
Does this replace tax advice?
No. The calculator models the statutory tax rate schedule and helps with planning reserves. Determining taxable income, structuring questions and the tax return belong in the hands of your tax advisor.
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