Borrower insurance: the often overlooked total cost

Borrower insurance: a key cost in any buy or rent decision

With mortgage rates around 3.6% in many European markets, most people focus on the nominal loan rate. The borrower insurance rate (taux_assurance), usually between 0.25–0.45% per year, is often treated as a detail. Yet it can account for up to 30% of the total cost of a mortgage. Ignoring it will completely distort any serious buy or rent comparison.

This article zooms in on one specific parameter of the buy-or-rent.net simulator: the taux_assurance (insurance rate). By adjusting it, you can see how insurance alone can tilt the balance between buying and renting, as much as loan rate, notary fees or property tax.

How the borrower insurance rate works

In most standard bank policies, the insurance rate is expressed as an annual percentage of the initial loan amount, and charged for the whole term of the loan. That makes the total insurance cost particularly high over 20–25 years.

Basic formula

For a mortgage:

• Principal: C
• Annual insurance rate: Ta
• Term in years: N

If the insurance is charged on the initial principal for the full term:

Total insurance cost ≈ C × Ta × N

Quick example: a 250,000 € loan over 25 years with a 0.35% insurance rate:

• Total insurance cost ≈ 250,000 × 0.0035 × 25 = 21,875 €

These 21,875 € come on top of loan interest, notary fees (7–8% for existing property, 2–3% for new-build), agency fees (3–5%), property tax and renovation. In a rigorous buy or rent analysis, leaving insurance out means massively underestimating the cost of buying.

Full example: insurance can exceed one year of net income

Let’s take a realistic scenario, which you can reproduce in the simulator:

• Purchase price: 300,000 € (existing property)
• Notary fees (8%): 24,000 €
• Agency fees (3.5%): 10,500 €
• Down payment: 30,000 €
• Loan amount: 270,000 €
• Term: 25 years
• Loan rate: 3.6%
• Insurance rate (taux_assurance): 0.35%

Monthly mortgage payment (without insurance)

At 3.6% over 25 years, the monthly payment excluding insurance is roughly:

• ≈ 1,370 € / month

Total interest over the term:

• Total interest ≈ 1,370 × 300 months − 270,000 ≈ 141,000 €

Borrower insurance cost

With Ta = 0.35% on 270,000 €:

• Annual premium ≈ 270,000 × 0.0035 = 945 €
• Monthly premium ≈ 79 €
• Total cost over 25 years ≈ 945 × 25 = 23,625 €

Bottom line: in this case, insurance represents about 17% of total interest (23,625 € vs 141,000 €), and more than 8% of the loan amount. For many households, 23,000 € is roughly one year of net salary.

Impact on the buy or rent comparison

If you ignore insurance in your calculations:

• You underestimate the buyer’s monthly payment by ~80 €
• You underestimate the total cost of buying by more than 20,000 €

In a 20–25 year buy or rent comparison, these 20,000–25,000 € can be enough to make the “rent and invest” option beat the “buy” option, or the opposite, depending on:

• Your investment rate (ETF, savings accounts, bonds…)
• The annual rent increase (linked to the rent index)
• Property tax increases over time
• Overall annual inflation

This is why setting the taux_assurance correctly in the buy-or-rent.net simulator is crucial.

Comparing two insurance rates: 0.20% vs 0.45%

Thanks to competition (alternative insurers, switching during the loan), borrowers can often lower their insurance rate. The simulator lets you see how a small change in taux_assurance affects your buy or rent outcome.

Base scenario

• Loan amount: 300,000 €
• Term: 20 years
• Loan rate: 3.6%
• Insurance on initial principal

Case 1: insurance rate 0.45%

• Annual premium = 300,000 × 0.0045 = 1,350 €
• Monthly premium ≈ 113 €
• Total over 20 years = 1,350 × 20 = 27,000 €

Case 2: insurance rate 0.20%

• Annual premium = 300,000 × 0.002 = 600 €
• Monthly premium = 50 €
• Total over 20 years = 600 × 20 = 12,000 €

Difference

• Total saving ≈ 15,000 €
• Monthly saving ≈ 63 €

15,000 € saved on insurance is equivalent to:

• A large share of your notary fees
• A full energy renovation budget to improve the property’s rating
• A significant lump sum invested in a diversified ETF portfolio

In a buy or rent simulation, if you stay a renter and invest 63 € per month at a 4% investment rate for 20 years, you end up with:

• Future capital ≈ 63 × ((1.04^20 − 1) / 0.04) ≈ ≈ 23,000 €

This is higher than the raw 15,000 € saving thanks to compound interest. The simulator can incorporate this investment rate to compare both strategies objectively.

Insurance and borrower profile

The taux_assurance depends heavily on:

• Age
• Health status
• Occupation (specific risks)
• Coverage level (death, disability, work incapacity…)

Two households with the same property price and loan rate can face very different insurance costs. In a data-driven buy or rent approach, you therefore need to:

• Simulate several insurance rates (0.20%, 0.30%, 0.45%…)
• Measure how these variations change the total cost of the “buy” option
• Compare these scenarios to the “rent + invest the difference” option

The buy-or-rent.net simulator lets you adjust this parameter and see in real time how it affects your total cost.

Insurance and other hidden costs of owning

Borrower insurance is only one of several hidden costs of homeownership. For a complete buy or rent comparison, you must also factor in:

• Property tax: from about 450 € to over 5,000 € per year depending on the city, with annual reassessment that can exceed inflation
• Home insurance: usually higher for owners than for tenants
• Maintenance and renovation: ongoing costs (often 1–2% of property value per year), plus energy upgrades
• Prepayment penalties: up to 3% of remaining principal or 6 months of interest

Among these, borrower insurance is one of the most predictable, since you know the rate and premiums from day one. It is therefore logical to include it precisely in any serious buy or rent analysis.

Inflation, interest rates and the total insurance cost

Annual inflation

With positive inflation, your nominal income and rents tend to rise over time, while:

• The borrower insurance premium, calculated on the initial principal, stays fixed in nominal terms
• Its share of your budget shrinks gradually

However, in cumulative real euros, the total insurance cost remains large. You should compare it to what that money could earn if invested at an investment rate above inflation.

Loan rate changes

When mortgage rates rise (for example to around 3.6%), the relative share of insurance in the total cost shifts. With a 1% loan rate, a 0.35% insurance rate is huge; at 4%, it is smaller but still meaningful. This is another reason to simulate multiple combinations of loan rate and taux_assurance.

Borrower insurance and investment strategy

From a wealth-building perspective, the real question is not just “buy or rent”, but:

• Buy + pay insurance vs Rent + invest the savings

If your yearly borrower insurance cost is 1,000 €, and as a renter you invest that 1,000 € per year at a 4% investment rate for 20 years, you get:

• Future capital ≈ 1,000 × ((1.04^20 − 1) / 0.04) ≈ ≈ 29,800 €

In a buy or rent simulation, this amount is compared against your net home equity after 20 years (market value – remaining debt – transaction costs – property tax – maintenance – insurance, etc.).

The point is not to claim that renting is better than buying, or vice versa, but to show that the total insurance cost is a cash flow that could, in an alternative scenario, be invested and compounded.

Using the simulator with the taux_assurance parameter

To properly measure the impact of borrower insurance on your buy or rent decision, you can:

Step 1: Enter a realistic insurance rate

• Young, healthy borrower: test 0.20–0.30%
• Older or higher-risk profile: test 0.35–0.45% or more

Input this value in the taux_assurance field of the simulator.

Step 2: Run several scenarios

• Scenario A: high taux_assurance (0.40–0.45%)
• Scenario B: medium taux_assurance (0.30–0.35%)
• Scenario C: optimised taux_assurance (0.20–0.25%) after switching insurer

For each scenario, compare:

• The total cost of buying (mortgage + insurance + property tax + upkeep)
• Your net position after X years (home equity)
• The situation as a renter if you invest the difference

Step 3: Interpret the results carefully

The simulator’s numbers give you a clear, quantified view, but they are not personalised financial advice. Your personal situation (job security, family plans, risk tolerance) still matters a lot. The calculations simply show that taux_assurance is not a minor detail, but a major driver in any buy or rent comparison.

Conclusion: a discreet parameter with a massive impact

Borrower insurance is often seen as a mandatory formality required by the bank. In reality, with a total cost frequently in the 20,000–30,000 € range over a full mortgage term, it weighs heavily on the buy or rent equation. A difference of a few tenths of a percent in taux_assurance can be worth several years of rent or a substantial invested portfolio.

So you should:

• Know your exact insurance rate and how it is calculated
• Always include borrower insurance in your buy or rent simulations
• Test multiple taux_assurance values in the simulator
• Compare “buy + insurance” vs “rent + invest” using a realistic investment rate

This article is for educational purposes only and does not constitute personalised financial advice. To see how your own borrower insurance affects your housing choice, simulate your situation on buy-or-rent.net.