New construction financing single-family house 150 - 160 sqm

Of course. A change in tax class only affects the monthly advance payment in the form of income tax withholding. The final settlement is made at the end of the year with the income tax return. With tax class 3, you pay less income tax monthly. The income tax withholding is credited against the income tax. So, if you pay less monthly, less is credited against the income tax payable at the end. The income tax payable depends on the taxable income. In that case, the tax classes are irrelevant.
A change in tax class is actually only useful in two cases.
1. To increase [Elterngeld] (the woman takes class III)
2. If you really depend on the extra money monthly.

Does this also apply if the main earner earns about 80% and the woman works part-time?

In the end, it always comes out the same. If you switch to 3/5, you ultimately get the tax advantage monthly through the salary payment. If you stayed in 4/4, there would be a big back payment with the tax return due to such large income differences. That’s why some switch their tax class specifically for parental allowance. In other words, the lower earner gets the better tax class to increase the calculation basis. Over the year, the total income is actually lower because the main earner pays higher taxes, but the difference is then refunded.

That's why I do not include this amount in the financing calculation. If things get tight, you can always make an additional repayment.

Then the entire property is completely unproblematic for you to finance. Don't worry. It only gets tight if you exceed your set budget by significantly more than 100k.

A change in tax class only affects the monthly prepayment in the form of wage tax. The final settlement takes place at the end of the year with the income tax return.

Prerequisite: you also file a tax return. You are not obliged to do so in this case. With III/V you are. Personally, I would always prefer to get something back rather than pay more. That's why I "kept" class I instead of II. Costs of childcare can really only be researched locally. Here with us, the amount depends on the number of children in the household and income and is independent of the age of the children (under 3 costs exactly the same as over 3), in the neighboring district a fixed amount for everyone regardless of income and higher than our maximum rate. You should definitely look into that... You don’t want to be caught off guard. In the end, it might even turn out that it’s not "worth it" for mom in tax class III working part-time because she hardly earns more than the childcare costs... (I would still recommend mom to stay in the profession).

Hello everyone,

Our cost framework is now at 95%. We will likely need a loan of 430 k€. The monthly installment will be around 1,300 €. Prepayments have not yet been included.
The house will be a "KFW 55 EE" --> 26 k€ subsidy.

There are two options for financing.
Option 1: Kfw as a subsidy option:

[*]404 k€ as an annuity loan from the bank. Planned fixed interest period 20 or 25 years. Interest rate not yet determined. --> 1,300 € installment
[*]26 k€ as a pure subsidy (Kfw 461) without Kfw loan

Option 2: Kfw as a loan option:

[*]280 k€ as an annuity loan from the bank. Planned fixed interest period 20 or 25 years. Interest rate not yet determined --> 800 € installment
[*]150 k€ Kfw loan with 26 k€ repayment subsidy (Kfw 261, 262): Term 30 years / 0.76 % / 10 years fixed interest. --> 500 € installment

With Option 1, I like the better long-term planning.
The only advantage of Option 2 would be potentially lower interest costs. But there remains a residual debt of around 100 k€ for the Kfw loan after the 10-year fixed interest period expires. This 100 k€ would then have to be refinanced at the conditions available in 10 years.
My gut feeling is more for Option 1.

What is your assessment?

Have about 90% the same constellation. Income, loan amount, and variant 2 (lower interest condition) chosen, so far one child, unmarried, and are in early 30s. Besides, we are still financing our 2200sqm property.

We dared to start under these conditions, and if not everything is finished immediately in the end, so be it.

Have saved good equity, seems frugal and that makes a big difference. Only downside, part-time mother,.... grit your teeth and keep working full-time. For example, we do it, but also because we have no sitting options (family) within 2.5 hours by car.

Conclusion: Let‘s go for you. :)