Can a bank reduce the mortgage if serious deficiencies become known during the purchase process?

Credit cut by the bank

Yes, a bank can and will reduce the mortgage if serious deficiencies become known during the purchase process. Since the bank determines the loan value on the basis of the current situation, deficiencies result in a direct deduction from the estimated market value. If this value falls, the maximum loan amount is automatically reduced, as the loan limit (usually 80%) must be strictly met. In extreme cases, the bank can even completely withdraw the financing commitment.

The revaluation of the loan value

At the heart of every mortgage loan is the bank's internal property valuation. If credit analysts learn of serious damage, a recalculation of the so-called loan value is initiated. In practice in 2026, this means that the expected restructuring costs are deducted directly from the originally estimated market value. The bank wants to ensure that if the property is sold, it is not left with a loss if the real market value is lower than the agreed purchase price as a result of the defects.

This process ensures that the bank's safety margin is maintained while the buyer must pay the difference. If the bank lowers the value of the property by 100,000 francs due to the deficiencies, the maximum loan amount falls by 80,000 francs in the case of 80 percent financing. The buyer must now raise this sum as equity or persuade the seller to lower the price accordingly. Without such an adjustment, the loan is often no longer affordability from the bank's point of view.

Effects on the loan rate and risk profile

In addition to the pure loan amount, the interest rate may also change if the bank has classified the property as riskier due to the deficiencies. A building with unstable statics or massive moisture damage worsens the overall financing risk profile. In some cases, the bank is willing to grant the original amount but requires an interest premium to compensate for the increased risk of default. This significantly burdens the buyer's long-term calculation and can have a negative impact on the affordability calculation.

In 2026, banks often also subject the payment of the mortgage to an obligation to make improvements. In such a scenario, part of the loan amount is withheld in a blocked account until the buyer can prove that the serious deficiencies have been professionally remedied. This serves to preserve the value of the pledged property and ensures that the property meets the standard required loan-to-value ratio payment. For the buyer, this means additional administrative effort and increased pressure when planning restructuring.

The role of the financing commitment and legal consequences

It is a common misconception that a written financing commitment is an irrevocable contract. Almost all bank confirmations contain reservation clauses in the small print, which provide for a final check of the quality of the object. If serious facts are concealed or discovered late, the bank can withdraw from the commitment without being liable for compensation. In this case, the bank invokes the loss of the basis of the transaction, as the nature of the security has significantly deteriorated.

This situation puts the buyer in a precarious position, particularly if he has already signed a reservation agreement or made down payments. A professional sales process should therefore always contain a clause which makes the purchase contract subject to a final credit approval. If this insurance is missing, the buyer is liable to the seller for the damage caused if the financing fails due to the defects discovered subsequently. A thorough technical check before applying for a loan is therefore the best protection.

Conclusion: Valuation beats purchase price

Can a bank reduce the mortgage? Yes, it even has to do it if the value of the security is no longer guaranteed. In the Swiss real estate market of 2026, the purchase price is only a guideline; the value of the building structure, determined independently by the bank, is decisive for financing.

In summary, serious deficiencies are not just a technical problem, but a massive financing risk. If such defects are discovered, buyers should immediately contact the bank and, at the same time, request a price adjustment from the seller. Anyone who deals proactively with the depreciation and restructures the financing on a realistic basis will avoid a failure of the purchase project at the last second. Transparency vis-à-vis the lender is the most important currency for a successful transfer of ownership.

glossary

• Loan value: The value of a property carefully estimated by the bank, which serves as the basis for maximum lending.
• Property appraisal: A systematic process for determining the market value, taking into account the situation, condition and restructuring needs.
• Due diligence phase: The phase of carefully examining a property for technical, legal and financial risks before the purchase.
• Share of own funds: The part of the purchase price that the buyer must finance from his own resources (savings, pension fund), usually at least 20%.
• Safety margin: The buffer between the loan granted and the actual value of the property to protect the bank from price fluctuations.
• affordability calculation: The bank's analysis of whether the running costs of the property are in healthy proportion to the buyer's income.