"We have to pay the tax."
Translation:Tenemos que pagar el impuesto.
It seems "tasa" should be correct since we don't know the context. Here is all I could find regarding the difference between "tasa" and "impuesto":
"Impuesto": is a "tributo" with no compensation levied on facts that reveal the economic capacity of a person.
"Contribuciones especiales": “tributos” that one must pay when their goods show an added value as a result of public activity, such as public works or new public services.
“Tasa”: is a “tributo” that one must pay for using public dominion or using public services (when they are not in competition with private ones, because then it would not be a “tributo”, a tax, but a “precio público” a “public price”).
Still confused as to why "tasa" was rejected. Maybe a native could "translate" for us?