BAFA funding after the start of construction works

Hello, we are currently building a house with a general contractor. In the contract, we have an air-water heat pump. Actually, by now I would also like to switch to a brine-water heat pump due to the subsidy. The problem here is that we are already building and the heating trade is part of our general contractor contract (even though this trade will only start soon). Is there any possibility to still claim the subsidy? What would happen, for example, if I conclude some kind of change contract directly with the general contractor or the heating installer, changing from an air-water heat pump to a brine-water heat pump? Does anyone have an idea?

That is regularly not a problem, because due to the lack of a heating load calculation, you will not yet have a concrete model in the contract, at best a series from a manufacturer. The BAFA accepts that. I consider a "change contract" to be rather dangerous, as that would mean that something concrete was already ordered and is now being corrected retrospectively. We had the GC prepare a sampling offer after the heating load calculation was created and based on that applied for the subsidy. The previous flat rate for heating type XY is credited in the contract and everyone is satisfied. This way you even have a complete invoice for the heating.

Exactly, we have a manufacturer with model series listed. According to the heating technician, I can still change my mind.

The question is whether BAFA requires proof for this. The requirements state that basically the contract conclusion counts (I don't have the exact wording in mind right now).

Yes, the documents must be submitted and will be reviewed.

Do I need an individual invoice for the heating with a general contractor? How does it generally work there?

The problem is that I would only pursue the brine-water heat pump if I could be sure to receive the subsidy. There is no hotline or anything like that at BAFA, right? I quickly couldn't find anything on their site.

An individual invoice definitely makes it easier, because you have to prove to the BAFA what the heat pump cost. That becomes difficult to impossible with an overall contract.

Well, everyone has the problem with security. Only when you apply for the payment with invoices and after completion does the BAFA check what is recognized and what is not. It's annoying, but unavoidable – see also the other threads regarding BAFA and KNX etc.

But they have a hotline and email support. However, it may take some time to get a response.