Non-binding, but very reliable
A financing confirmation is generally not yet a binding commitment to granting a mortgage. The financing is, as a result, not yet secured. Lenders protect themselves against legal claims with formulations such as “We hereby confirm that we are prepared in principle to finance the single-family home XY with a mortgage...” or “Subject to final review, we hereby confirm that...”. They can revoke this commitment at any time if, for example, they have new information about your creditworthiness or the condition or market value of the property you want to acquire.
Practice shows that financing confirmations are drawn up very carefully. And although they aren’t binding, they are generally reliable.
In many cantons, an irrevocable promise to pay from the lender is required instead of a financing confirmation for the final notarization of the purchase contract. An irrevocable promise of payment is the lender’s commitment to transfer the purchase price amount. The lender makes an irrevocable promise to pay once the legally binding mortgage agreement has been signed by the borrower and other conditions have been fulfilled.
The mortgage agreement outlines all the contractual details between you and your lender. By this point, however, your creditworthiness and the property you are financing have already been thoroughly checked.