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IRR vs ROI for German Property: The Simple Way to Avoid a Misleading Deal

10 min read

When people look at a property deal in Germany, they often ask one question:

“What’s the return?”

The tricky part is that “return” can mean several different things. Some people mean ROI. Some really mean cash-on-cash return. Others are talking about IRR. All three are useful, but they do not answer the same question.

In plain English:

  • ROI tells you how much you made compared with what you put in.
  • Cash-on-cash return tells you how much cash flow your own money produces in a year.
  • IRR tells you the annualised return on your own cash after considering the full journey: buying, financing, renting, holding and selling.

If you buy a property with cash and only care about the final gain, ROI may be enough. But once you add a mortgage, rental income, maintenance, acquisition costs and a future sale, ROI becomes too flat. It is like judging a film by the last frame: you see the ending, but not the story that got you there.

This article uses a simplified Berlin apartment example to show when ROI helps, when it misleads, and why IRR is often the better metric for a leveraged German property investment.

1. The three metrics you should not mix up

ROI: simple, useful, but easy to misuse

The basic idea behind ROI is straightforward:

ROI = Net gain ÷ Investment cost × 100%

Investopedia defines ROI as a measure of the profit or loss generated by an investment relative to its cost, usually expressed as a percentage.1

For example, if you invest €100,000 and later get back €120,000 after costs, your net gain is €20,000 and your ROI is 20%.

But here is the missing question:

Did you make that 20% in one year or in ten years?

A 20% gain in one year is very different from a 20% gain over a decade. ROI by itself does not automatically account for time, inflation, the timing of cash flows or the risk you took. That makes it a useful first-glance metric, but a weak stand-alone decision tool for a long-term rental property.

Cash-on-cash return: the “what did my money earn this year?” metric

In property investing, many people say “ROI” when what they really want to know is:

“How much annual cash flow do I get on the equity I put into the deal?”

The more precise term is cash-on-cash return.

Cash-on-cash return = Annual pre-tax net cash flow ÷ Initial cash invested × 100%

For a German property, “initial cash invested” should not mean the down payment only. It should include buyer-side acquisition costs such as Grunderwerbsteuer, notary fees, land registry fees and broker commission if applicable.

Cash-on-cash return is helpful because it focuses on real money moving in or out of your account during the holding period.

Its limitation is just as important: it ignores the future sale, mortgage amortisation and the value of your equity at exit.

IRR: the metric that puts time into the model

IRR stands for Internal Rate of Return. It is the discount rate that makes the net present value of all cash flows equal zero. CFA Institute describes IRR in exactly that way: a discount rate that makes the NPV of an investment zero.2

For a property deal, IRR typically includes:

  • Year 0: down payment, transfer tax, notary, land registry, broker fee and initial renovation;
  • Years 1–10: rent, non-recoverable costs, maintenance, vacancy, mortgage payments;
  • Exit year: sale price, remaining loan balance, selling costs and, in a full model, tax effects.

So IRR answers a better investment question:

“From purchase to exit, what annual compound return does this property generate on my own cash?”

That makes IRR especially useful for German property deals with leverage and multi-year rental cash flows.

2. Why German property makes a simple ROI especially risky

German acquisition costs are large, and they differ by federal state.

The biggest one is Grunderwerbsteuer, the real estate transfer tax. The federal base rate is 3.5%, but the actual rate depends on the Bundesland. According to the DNotI table dated 28 January 2026, current rates range from 3.5% in Bavaria to 6.5% in Brandenburg, North Rhine-Westphalia, Saarland and Schleswig-Holstein; Berlin is at 6.0%.3

On top of that, you should usually budget for:

  • Notary and land registry: often around 1.5%–2.0% of the purchase price. Interhyp states that notary fees are roughly 1.0%–1.5% and land registry fees are usually around 0.5%.4
  • Broker commission: if a broker is involved, the buyer often pays around 3.57%, though the actual amount depends on the contract and region. For consumer purchases of apartments or single-family houses, the German Civil Code contains specific rules on commission sharing; for example, §656c BGB requires equal commission arrangements when the broker acts for both parties.5
  • Renovation, due diligence and financing costs: not every deal has these, but leaving no buffer is usually optimistic.

This means a €500,000 property is not simply “€500,000 plus a mortgage payment”. The buyer may need 8%–12% of the price in additional cash at acquisition. If you leave that out, both ROI and IRR will look better than they really are.

3. Example: a €500,000 apartment in Berlin

The following example is simplified. It is not a rent forecast or investment recommendation. Its only purpose is to show how the metrics behave.

Assume you buy an apartment in Berlin:

Input Assumption
Purchase price €500,000
Down payment 30%
Loan amount €350,000
Mortgage rate 4.0% p.a.
Mortgage term 25-year annuity
Monthly cold rent €2,500
Non-recoverable costs, maintenance and vacancy reserve €450 / month
Holding period 10 years
Capital growth assumption 2.0% p.a.
Selling costs 5% of sale price

How much cash do you really need at purchase?

Item Calculation Amount
Down payment €500,000 × 30% €150,000
Grunderwerbsteuer €500,000 × 6.0% €30,000
Notary + land registry €500,000 × 2.0% €10,000
Broker fee, if buyer pays 3.57% €500,000 × 3.57% €17,850
Total initial cash invested — €207,850

A common mistake is to use only the €150,000 down payment as the denominator. Another is to underestimate acquisition costs and use a figure such as €32,000. Both make the return look too optimistic.

If there is no broker fee, your initial cash falls to roughly €190,000. If there is a broker fee, €207,850 is the more realistic starting point.

What does the first-year cash flow look like?

A €350,000 loan at 4% over 25 years gives a monthly payment of roughly €1,847.

Item Monthly amount
Cold rent €2,500
Non-recoverable costs, maintenance and vacancy reserve -€450
Mortgage payment -€1,847
Pre-tax monthly net cash flow about €203
Pre-tax annual net cash flow about €2,436

The first-year cash-on-cash return is therefore approximately:

€2,436 ÷ €207,850 ≈ 1.2%

This does not automatically mean the deal is good or bad. It simply tells you that, in year one, the property is not mainly a cash-flow play. Much of the investment case depends on amortisation and future resale value.

4. What about the 10-year IRR?

Now continue with the same assumptions:

  • property value grows by 2% per year;
  • the property is sold after 10 years;
  • selling costs are 5% of the sale price;
  • the remaining mortgage is repaid at sale;
  • personal income tax, depreciation and German private sale tax rules are excluded for simplicity.

A €500,000 property growing at 2% per year is worth about €609,500 after 10 years. After 5% selling costs, net sale proceeds are about €579,000. The remaining loan balance after 10 years is about €250,000, so the equity released at sale is roughly €329,000.

If we combine the initial -€207,850 cash outflow, annual rental cash flows and the final sale proceeds, the 10-year pre-tax IRR is approximately:

about 5.7% p.a.

If there is no broker fee and the initial cash invested falls to about €190,000, the pre-tax IRR rises to about 6.7% p.a.

That difference is the lesson: the same property can lose roughly one percentage point of IRR simply because the buyer pays broker commission. For a long-term investor, that is not a rounding error.

5. Why positive cash flow does not automatically mean a great investment

The example produces around €200 of pre-tax monthly cash flow. That looks comfortable. But the IRR comes from three sources:

  1. a small positive monthly cash flow;
  2. tenant-funded mortgage amortisation;
  3. a future sale at an assumed higher price.

What if the property does not appreciate?

Scenario Assumption 10-year pre-tax IRR
Conservative 0% annual price growth about 1.9%
Base case 2% annual price growth about 5.7%
Optimistic 3% annual price growth about 7.4%

The point is not to forecast Berlin prices. The point is that IRR is very sensitive to the exit value.

If a deal only works when you assume steady price growth, it is not a low-risk cash-flow asset. It is a leveraged investment with a meaningful resale-price assumption.

6. When should you use ROI, cash-on-cash and IRR?

Use ROI when you want a quick total-profit view

ROI is useful for questions such as:

  • How much did I invest in total?
  • How much did I get back after costs?
  • What was the overall profit as a percentage of cost?

If you have already sold the property and want a simple historical summary, ROI is easy to understand.

Use cash-on-cash return when you care about holding-period pressure

Cash-on-cash return helps answer:

  • Is the property cash-flow positive this year?
  • How efficiently is my equity producing annual cash flow?
  • After mortgage payments, non-recoverable Hausgeld, maintenance and vacancy, how much cash is left?

This matters because a property can look attractive on a 10-year IRR basis but still require you to cover monthly shortfalls along the way.

Use IRR when you compare full investment cases

IRR helps answer:

  • What annualised return does the project generate from purchase to sale?
  • Does a higher-leverage or lower-leverage structure use equity more efficiently?
  • Which deal looks better across Berlin, Hamburg, Munich or Leipzig once acquisition costs differ?
  • What happens if the price-growth assumption falls from 2% to 0%?

IRR is powerful, but not perfect. CFA Institute cautions that IRR is a discount rate and that it only resembles a true rate of return under certain assumptions, including reinvesting interim cash flows at the same IRR.2 Very high IRRs can also be distorted by the timing of early cash flows.

So do not look at IRR in isolation. Use it together with cash flow, debt risk and exit assumptions.

7. Seven inputs German buyers often forget

To make your ROI and IRR closer to reality, do not forget:

  1. Grunderwerbsteuer: use the state-specific rate, not a national average.
  2. Notary and land registry: usually estimate around 1.5%–2.0%.
  3. Broker commission: include it in initial cash if the buyer pays it.
  4. Non-recoverable Hausgeld: not every cost can be passed on to the tenant.
  5. Maintenance and vacancy reserve: stress-test even if the flat is currently rented.
  6. Selling costs: broker fees, negotiation margin and loan breakage costs can affect exit proceeds.
  7. Tax effects: rental income tax, depreciation and German private sale rules can change the after-tax IRR.

The model in this article is pre-tax. Before making a purchase decision, ask a Steuerberater to model personal tax, depreciation, deductible expenses and potential sale-tax effects.

8. How to read the German Immo Flow output

Do not focus on one headline number. Read the results in this order:

  1. Monthly cash flow: tells you whether you need to add money every month.
  2. Cash-on-cash return: shows how efficiently your initial cash is producing annual cash flow.
  3. Cumulative cash flow: shows total cash in or out during the holding period.
  4. IRR: shows the annualised return from purchase to sale.
  5. Sensitivity checks: lower rent by 5%, raise maintenance, set price growth to 0%, and see whether the deal still works.

A good property investment should not only look good in the most optimistic version of the spreadsheet. It should still be manageable under conservative assumptions.

9. FAQ

Is a higher IRR always better?

No. A high IRR can come from a strong deal, but it can also come from high leverage, a small initial cash investment, optimistic appreciation assumptions or unusually early cash inflows. Always check debt, cash-flow stability and exit assumptions.

Can IRR be positive if monthly cash flow is negative?

Yes. If price appreciation, loan amortisation and the final sale proceeds are large enough, IRR can still be positive. But this type of deal depends more heavily on the exit and may require you to fund monthly shortfalls.

Which metric is best for a German rental property?

For a long-term rental property, IRR is usually the better full-project metric. But cash-on-cash return is just as important for understanding holding-period pressure. Use both.

Why is the IRR in this example lower than in many quick online estimates?

Because the model includes Berlin’s 6% transfer tax, notary and land registry costs, and a possible buyer-side broker fee. Omitting acquisition costs makes the deal look better, but it does not reflect the cash you actually need.

10. Key takeaway

ROI, cash-on-cash return and IRR are all useful, but they answer different questions:

  • ROI: How much did I make overall?
  • Cash-on-cash return: How much annual cash flow does my own money produce?
  • IRR: What annual compound return does the full project generate from purchase to sale?

If you only look at ROI, you may ignore time. If you only look at cash flow, you may miss the effect of amortisation and exit value. If you only look at IRR, you may rely too heavily on optimistic sale assumptions.

The safer approach is to put all acquisition costs, financing, rent, holding costs and exit costs into one model — then compare cash flow, cash-on-cash return and IRR together.

That is what German Immo Flow is built for: less gut feeling, more transparent assumptions, and a clearer view of whether a German property deal actually makes sense.

Disclaimer: This article is for general education and uses a simplified model. It is not tax, legal, financing or investment advice. German property transactions depend on personal tax circumstances, loan terms, rental contracts, state-specific rules and deal structure. Speak with a Steuerberater, notary or independent mortgage adviser before making a purchase decision.

References

  1. Investopedia, “What Is Return on Investment (ROI) and How to Calculate It”, updated 18 February 2026. https://www.investopedia.com/terms/r/returnoninvestment.asp ↩

  2. CFA Institute, “A Reality Check on Private Markets: Part II”, 15 November 2024. The article explains that IRR is the discount rate that makes NPV equal zero and discusses the reinvestment assumption behind IRR. https://rpc.cfainstitute.org/blogs/enterprising-investor/2024/a-reality-check-on-private-markets-part-ii ↩ ↩2

  3. Deutsches Notarinstitut (DNotI), “Aktuelle Grunderwerbsteuersätze”, status 28 January 2026. https://www.dnoti.de/fileadmin/user_upload/Arbeitshilfen/Steuerrecht/Aktuelle_Grunderwerbsteuersaetze_Stand_28_01_2026.pdf ↩

  4. Interhyp, “Grundbuch- und Notarkostenrechner”. The page states that notary costs are roughly 1.0%–1.5% of the purchase price and land registry fees are usually around 0.5%, for a total of about 1.5%–2.0%. https://www.interhyp.de/notar-grundbuchkostenrechner/ ↩

  5. Bürgerliches Gesetzbuch (BGB), § 656c, “Lohnanspruch bei Tätigkeit für beide Parteien”. https://www.gesetze-im-internet.de/bgb/__656c.html ↩