Understanding Property Finance: Equity, Repayment, Fixed Rate

Anyone thinking seriously about buying a flat or a house for the first time quickly runs into a flood of terminology: annuity, borrowing rate, initial repayment, fixed interest period, residual debt, overpayment. The jargon sounds intimidating, but it really only describes three decisions that are yours to make. Understand these three levers and you understand your mortgage — and you will also notice when someone is trying to sell you something that doesn't fit. This article explains them one by one, honestly and without promises about interest rates.

Lever 1: Equity

Equity is the money you contribute yourself instead of borrowing it from a bank — savings, a home savings contract, sometimes an interest-free family loan. It has two jobs. First, every euro of your own money reduces the loan amount and therefore the interest burden over the entire term. Second, banks see more equity as lower risk and typically offer better terms in return. How much is "enough" depends on the individual case; blanket percentages are only rough guidance, not fixed truths.

The often underestimated item: additional purchase costs

One item is regularly forgotten when counting equity: the additional purchase costs. These are costs on top of the actual purchase price that many banks are reluctant to finance. The rule of thumb therefore is: cover these costs from your own pocket if at all possible. They fall into several categories:

• Property transfer tax: Due at the time of purchase and varies considerably by German federal state — rates broadly range from around three and a half to six and a half per cent of the purchase price. Which rate applies depends solely on which state the property is in.
• Notary and land registry: The purchase contract must be notarised, and the change of ownership and the mortgage charge must be registered in the land registry. These fees typically come to around one and a half per cent of the purchase price.
• Estate agent commission: Only applies if an agent is involved. The amount varies by region, and since a legislative change, the commission for owner-occupied residential properties is usually split between buyer and seller.

In total, depending on the state and whether an agent is involved, the additional costs can quickly reach a low to mid double-digit percentage of the purchase price. For a property costing 400,000 euros, that is roughly 30,000 euros without an agent — considerably more with one. This is money that does not appear in the purchase price itself, and it can easily blow the financing if you have not factored it in from the start.

Lever 2: Repayment

Repayment is the portion of your monthly payment that actually pays down the loan. The other portion is interest. Together they make up the annuity — the constant monthly payment of a classic annuity mortgage. The trick behind it: with each payment the outstanding balance falls slightly, so the interest portion of the next payment decreases, and because the total payment stays the same, the repayment portion automatically grows. The pay-off accelerates on its own, the longer it runs.

What matters is the initial repayment — the percentage of the loan amount you pay back in the first year. Think of it as a speed dial: the higher the initial repayment, the sooner you are debt-free and the less total interest you pay — but the higher your monthly payment.

Example calculation: repayment

The following calculation is an example with stated assumptions, not a forecast. Assume: loan of 300,000 euros, agreed borrowing rate of 3.5 per cent per year. We are comparing only the initial repayment.

• 2% initial repayment: Annuity = (3.5% + 2%) of 300,000 € = 16,500 € per year, i.e. 1,375 € per month. In year one, 10,500 € goes on interest and 6,000 € on repayment. At a constant rate the loan is paid off in around 30 years.
• 3% initial repayment: Annuity = (3.5% + 3%) of 300,000 € = 19,500 € per year, i.e. 1,625 € per month. In year one, 10,500 € interest, 9,000 € repayment. The loan is cleared in just over 22 years.

The extra 250 euros a month therefore cuts the term by roughly eight years. Calculated over the full term, the faster option saves approximately 47,000 euros in interest (around 138,000 instead of around 185,000 euros — rounded example figures). A higher repayment rate is not an end in itself; it saves real money, as long as the higher payment remains sustainable. You can model different repayment and purchase scenarios yourself using the Investment Calculator to get a feel for the levers.

Lever 3: Fixed interest period

The fixed interest period determines how long the agreed borrowing rate is guaranteed — for example 10, 15 or 20 years. It is a bet on the future that can go either way, which is precisely why there is no universally "correct" answer here.

A short fixed period often comes with a slightly lower rate, but leaves you with a risk: when the fixed period expires, almost always a residual debt remains, which you must refinance at the then-prevailing terms. If rates have risen, your payment increases noticeably. A long fixed period usually costs a small rate premium but buys you planning certainty for many years. Which option fits better depends on how much fluctuation your household can absorb — not on an interest rate forecast that nobody can make reliably.

Two terms are important in this context:

• Overpayment right: the contractually guaranteed option to pay additional lump sums on top of the regular payment — for example from a bonus or inheritance. Every overpayment reduces the residual debt directly and saves interest. Make sure this right is in the contract.
• Forward mortgage: the idea of locking in the interest rate for a refinancing several years in advance. This can provide certainty but is itself a bet and comes with its own costs — mentioned here only as a term you should know.

What the monthly payment should realistically look like

The most important question comes last: what payment can you sustain permanently? Do not rely on a fixed percentage of income — these rules of thumb circulate widely but land differently for every household. More useful is an honest household budget: set your actual monthly income against all recurring outgoings — living costs, insurance, car, reserves. What remains is your room for the payment, and not right to the last euro. Leave a deliberate buffer for repairs, savings and the unexpected; owning a home brings new costs that a landlord previously covered.

Typical mistakes

• Forgetting the additional costs. Anyone who plans only for the purchase price will suddenly face a five-figure shortfall at the notary appointment.
• Calculating too tightly. A payment with no buffer becomes a burden the moment the car breaks down or income fluctuates.
• Setting the repayment too low. A very low initial repayment makes the payment comfortable but leaves a large residual debt once the fixed period expires.
• Overlooking the overpayment right. Without this clause you give up the flexibility to reduce the loan quickly when money comes in.
• Focusing only on the interest rate. The lowest rate is of little use if the fixed period, repayment and repayment options do not suit your life situation.

Conclusion

A mortgage is not a black box. Equity reduces the debt and improves the terms; the initial repayment determines speed and total cost; the fixed period distributes the interest rate risk — you now understand all three levers and can adjust them to your situation. Anyone who also factors in the additional costs honestly and sets the payment using a real household budget rather than a rule of thumb is making a decision with their eyes open. More articles on property purchase and financing are in the Real Estate & Mortgages rubric.

This article is not investment, tax or financial advice.