Deadline for approval exemption and child construction allowance

Hello everyone,

a quick question for you. For our new building, a permit exemption is possible. How is it with the proofs for the Baukindergeld? No building permit is issued, you only receive a confirmation of receipt for the application.
Now I have received contradictory information about which deadlines apply. Is it enough if I have the confirmation of receipt by 31.03.2020 or do I have to start construction by 31.03.2021 at the latest (the latter will not work).
I also called the KfW. The lady on the phone seemed as if she had heard this question for the first time. Her first answer was that we must start construction by 31.03.2021 at the latest. Then she reconsidered and said that the confirmation of receipt is sufficient.

The little information available on this topic on the internet is not always entirely clear to me.

The KfW information sheet states: New buildings are eligible for funding if the building permit was issued between 01.01.2018 and 31.12.2020. Projects that only require notification according to the respective state building law are eligible for funding if the responsible municipality has gained knowledge through the building notification in accordance with the respective state building code and the execution of the project was allowed to start earliest between 01.01.2018 and 31.12.2020.

Here I would interpret the last sentence as follows: I am allowed to start construction earliest between 01.01.2018 and 31.12.2020 (in the future 31.03.2021). According to this, even after the key date?

I would like to know your level of knowledge on this topic.

Best regards

and the execution of the project was allowed to begin no earlier than between 01/01/2018 and 12/31/2020.

You must be ALLOWED to start construction. When all your documents have been submitted to the building authority and checked for completeness, you will receive a certificate of completeness. With us, construction may begin 3 weeks after this certificate. Depending on the federal state, there are differences in the details. However, the acknowledgment of receipt alone is not sufficient. Also, it is not necessary to actually begin.