of course a refund will also refund the VAT. Alas Nikolaus now needs to rollback all the transactions in his book-keeping and between GDC and tax office, but the VAT is not supposed to stay at tax office when the payment gets returned. Probably the Neo900 UG also has to pay VAT to (a different) tax office as soon as donations come in, so GDC refunds complete amount incl VAT to you (minus fees and expense already done), you are free to donate any amount to Neo900 UG, and Neo900 UG has to pay VAT to tax office again. In any case there's only one time VAT being paid, in the end. All this been a huge part of the problem we had with direct transfer of funds from GDC to Neo900 UG, though I don't know details of the troubles this caused inside GDC accounting.
On a sidenote: the UG received the tax ID today, so one more step completed.
Sorry I can check details on how to proceed on Monday the earliest, my tax advisers don't do overhours at weekend :-)