Reduced value-added tax until the end of 2020. Procedure for invoices?

With a down payment, VAT arises upon receipt; there is only no obligation to issue an invoice.

However, this only concerns the entrepreneur's obligation to remit the tax to the tax office. It has nothing to do with the customer. The same applies to "incorrect" invoices, e.g. incorrectly stated 19% instead of the reduced rate (or 19% instead of 16% in July), where the entrepreneur also has an obligation to remit the collected (excess) tax.

Wait, the entrepreneur is only obliged to make an advance payment of the entire taxes on advance payments themselves, which is then offset against the actual amount at the end of the project. Please correct me if I am wrong.

However, this only concerns the obligation of the entrepreneur to remit the tax to the tax office. It has nothing to do with the customer. The same applies to "incorrect" invoices, e.g. incorrectly stated 19% instead of reduced rate (or in July 19% instead of 16%), there too the entrepreneur has an obligation to remit the collected (excess) tax.

Yes... And what does that have to do with the quote I wrote? The customer, unless they are entitled to input tax deduction, never has anything to do with the remittance of VAT (and even then they do not have to remit anything).

You have used "Entstehung der Steuer" in such a way that it could be understood as if it meant the amount of the tax is finally fixed at the time of payment.

Wait, the entrepreneur is only obligated to make an advance payment of the entire taxes on prepayments themselves, which is then offset against the actual amount at the end of the project. Please correct me if I am wrong.

The entrepreneur is always subject to a certain advance notification period. Basically, it is the quarter, but for larger entrepreneurs it is almost always the calendar month (starting from tax of 7,500 in the previous year).

You used "Entstehung der Steuer" in such a way that one could understand it as if the amount of tax is finally fixed at the time of payment.

Entstehung der Steuer – that’s what the paragraph is called – only means at what point in time the entrepreneur must remit (or report) it to the tax office. And for prepayments, he must do this by the end of the respective advance notification period in which he received the prepayment.
14c and the like then come into effect in their own advance notification period.

But I understand what you mean – no, the final tax is (of course) not fixed by this, but the tax office does not wait for the project to be completed in case of prepayments; rather, it collects the VAT for the revenue received up to that point in advance.

Exactly, that's why I pointed it out, because actually this thread is about what the customer has to pay in the end.