Private loan - what should be considered?

The 5.5% are mentioned in a ruling by the BFH and hardly anyone within the family will probably grant a loan with 3.8%. I would rather go to the bank than pay 3.8% interest to a relative. In this respect... you gave the advice to evade taxes, not me ;)

Why? If the interest rate were actually 5.5% or even 6% or 7.6%? Then 3.8% is already quite fair. I paid my father 3% interest when consumer loans would have been around 4-5% (for me).

I haven't understood this yet, . Your uncle wants to give "with warm hands," which is commendable. But the nature of a loan is its repayment. Isn't that contradictory? If your uncle generates interest income, he must also pay taxes on it. How do you want to handle the securities, or is everything based on trust? "Family" sounds like you are at least married – what happens in the event of a separation? Normally, there would be a gift here. That results in gift tax for you. Simply put: the uncle pays a few bills.

The 5.5% are mentioned in a ruling by the BFH

The 5.5% are the discount factor for non-interest-bearing liabilities. I believe the maturity was also a topic in the ruling. Neither is relevant here. For gift tax, only the third-party comparison can be considered.

Thank you very much for your detailed answers. I think we will use one or the other tip here :)