Is financing feasible this way? Are the fixed costs okay or too high?

Hm...apart from the telecommunications costs, I don't think the expenses are high. Some are certainly set rather too low. Please consider whether you really only pay €17 car tax per year and only €90 insurance per year, that can hardly be true, just like the dog tax almost certainly does not amount to only €17 per year. We also live in Lower Saxony and have two dogs, you probably mean monthly costs for all these things. Household insurance and dog liability insurance at €40 per year also seems quite cheap to me, but €40 per month is too much. If it really is only €40 per year, I would like a tip from you (also gladly as a private message) on where to get that. The car costs of €525 per month only add up if you drive a small car. In my opinion, that no longer fits with somewhat larger cars. Do you include depreciation, vehicle inspection, servicing, etc., or is that just the monthly installment, where possibly a final payment is due after a few years?

I wrote that we have broken down the annual costs to the month. Annual means they occur yearly. So everything is multiplied by 12.

For the car, it is only the monthly rate. Both cars are returned after 4 years and a new one is chosen. At this point, adjustments can be made in the area of car costs. TÜV and inspection are not included here and will be added later.

Household contents/liability/legal protection are around €400, plus about €80 liability for two dogs.

700€ for health insurance is extremely high

Just for comparison: 661 euros/month voluntarily insured under public health insurance (1 adult, 2 children in this case). It's my own fault ...

I would like to cut something,

Immediately I notice 120 euros for telecommunications. Do you really need that? Every little bit helps ...

As mentioned, the health insurance each also includes a disability insurance. Without it, it's about 500€ for pure private health insurance.

I agree on the mobile phone costs. There is the landline and internet once. That should be okay with 35€. Regarding the phones themselves, we can definitely adjust something. Both had prepaid, but were permanently without reception. I think in the long term we will take another look at it,

Ok, then I misread. If the cars are then not taken over, the rate does not go down either. So no potential. But do you really pay 40 per month for liability insurance?!

well, 40x12 is 480€. This includes liability, dog liability, household contents, legal protection... And the car installments can indeed go down if we took a cheaper car. For example, we financed mine with a residual payment of 6000€ because we once thought about taking it over. But for various reasons, it doesn't make sense. If we had financed it with a higher residual payment, the installment would also be cheaper.