Question about cash discount settlement in advance payment

Hello everyone,

I have a question about cash discount since we have just received the final invoice from the structural builder.
It was agreed upon a 2% cash discount which we have always deducted and paid on time for the 4 installment payments.

The "payment flow" looked like this:

1st installment invoice: €20,000. 2% cash discount We pay: €19,600

2nd installment invoice: €36,000. 2% cash discount We pay: €35,280

3rd installment invoice: €25,000. 2% cash discount We pay: €24,500

4th installment invoice: €30,000. 2% cash discount We pay: €29,400

For the final invoice he now calculates as follows:

Total invoice amount: €121,000 - the 4 paid installment invoices (total €108,780) results in a remaining amount of €12,220.

My question now:

To calculate the remaining debt, he must take the non-discounted amounts (so the €20k + €36k + €25k + €30k), right?
Otherwise, the cash discount would not benefit me at all if it is added back later? Or am I mistaken here?

It would be great if you could give me some advice on this.

Thank you very much for your feedback!

In my opinion, you are right. The structural engineer has to calculate with the invoice amounts and not with the amounts paid. So if there are still €10,000 to be paid now, you can of course deduct the 2% from that again. If this was agreed in writing, then it should be like that.

Who checks your invoices? That person should get in touch with the structural engineer again.

He has to calculate as if there had never been any discount.

So if he wants a total of (without discount) €121,000 and then grants a 2% discount on it, he now still gets €10,000 before discount. And not €12,220.

If everything is correct and you pay on time, he now receives €9,800 from you.

Then you have paid €118,580 if you always take the discount.

What he is doing there is perhaps a well-intentioned attempt to get more money. I can hardly imagine that anyone there doesn’t know what they are doing / trying.

Outstanding remaining payment 9,800 euros. (All information of course without guarantee)