This is not as simple as it looks, and I am not sure I have worked it out correctly, but I have looked at the on-line forms for tax payment provided by a couple of banks, and I have seen that "Tipo de recaudación" offers two options "ingreso" and "devolución," so presumably the form (which has been linked to a means of payment like a credit card or an account" can be used to make tax payment or to receive refunds. That leaves you with the literal translation "Type of revenue (or collection if you like): Payment or refund", which seems a bit strange to me, but does not seem so to the AET. This explains (sort of) my proposal, although in your case, if a payment is involved, simply "Type of revenue: (tax) payment" would work.