Credit vs Cash Payment

As wabe already pointed out, there is almost no saving through borrowing in Germany anymore, unless it is a project for commercial rental... it is better to apply for funding, then savings can materialize

I agree, this is a pure calculation task. But I think that with interest, compound interest, and processing fees you will pay more than you save in taxes.

Of course, it is difficult to answer such a question in a forum without knowing the exact background.... I suggest you go to the bank and get advice. You can openly discuss your thoughts. A good bank advisor will certainly be able to advise you neutrally!

but also consider that interest can also be positive... of course your credit interest is lower, especially in Switzerland... but in business administration it is called imputed interest so calculate like this equity ratio of 50% (so pay half) then you get subsidies because you cannot pay everything out of your own pocket (that takes time, you can expect that) then you make a reasonable financing deal with the bank, for example a building savings contract where the bank is registered as the beneficiary then you look at the interest on the loan and the tax savings (through the building saver there could be reasonable conditions) and then you also calculate interest on the money you have left (depends on how you invest it, but for example you should be able to get German federal bonds with an interest rate of 4.5% over a 5-year term this is how it is calculated in a large company or by a corresponding advisor the question is only whether it is worth the effort for you

Your friend would be right about the tax savings, but you also pay interest to the bank. So you have to calculate exactly which side the balance is on, profit or loss! It is always better to pay in cash, as you immediately become the owner, but you have spent all or most of your savings.

If you have the money, as you say, on the side, I wouldn’t take out a loan but pay yourself. A loan means interest and compound interest. And you somehow always have in the back of your mind that you owe someone money, I think.