To fully understand what “ground rent” means in the UK it is necessary to take a look before to the differences between “freehold” and “leasehold” (what you are probably aware of). Freehold is what we here in Spain understand as “propiedad o dominio absoluto”, and “leasehold” would correspond to “derecho de arrendamiento/inquilinato” (not “alquiler”, because there can be some differences, particularly concerning the rental period involved). This means that if you are a leaseholder you are not proprietor of the ground you live on. You are probably Argentinian, as per your profile, but I think this works more or less the same in your country too.

I am posting a useful link in Spanish that provides a good analysis of the differences between “freehold” and “leasehold” in the UK. With regard to your specific question, you are on the right track with your initial translation proposal. What puzzles me a bit is that final sentence stating “residential ground rent income in not based on occupancy”. Despite of this and the lack of the full context, I suggest “renta por el arrendamiento del terreno/suelo” as a translation for “ground rent”. If there is an even more specific term in Argentina, this is something I do not know, but a translation such as “renta por arrendamiento del terreno” is comprehensible everywhere, I think.

Final remark: Since ground rent is the money paid by leaseholders to the owner of the ground where the building has been built, I think it is necessary to mention “terreno/suelo” in the translation.

This is the link I mentioned before. It accurately explains the differences between freehold and leasehold on the one hand, but also distinguishes the two types of leasehold on the other hand. The second leasehold type was introduced by the Commonhold Act 2004, according to this information:

http://www.icamalaga-blog.com/2013/03/aula-de-ingles-juridic...

En esta entrada vamos a referirnos al Derecho inmobiliario inglés, no exento de cierta complejidad de cara a entender alguna de sus figuras jurídicas. De conformidad con éste, existen dos tipos de derechos (two types of estates): freehold y leasehold. Dejando de lado el hecho de que en última instacia todo pertenence a la Corona -si bien sus súbditos desconocen por regla general esta relación con su soberana-, freehold parece claramente corresponder a nuestro derecho de propiedad, tal y como nosotros lo entendemos. Si eres el propietario (freeholder) de un inmueble (premises), lo eres hasta que falleces o decides disponer de dicho bien (until you decide to dispose of it). El concepto que ofrece una mayor dificultad a la hora de entenderlo y tratar de trasladarlo a nuestro ordenamiento para encontrar una equivalencia es el leasehold. En una primera acepción, lease es sinónimo de tenancy agreement, lo cual nos lleva al concepto de arrendamiento. Pero cuando nos encontramos con que alguien "compra un leasehold" por 99 ó 999 años, esta equiparación queda fuera de juego.

[Second type of leasehold after the Commonhold Act 2004. This second leasehold type is what might apply to your case and explains what “ground rent” means]

Para poder entender mejor esta segunda acepción del leasehold tenemos que referirnos a la propiedad horizontal en el ordenamiento objeto de estudio. Hasta 2004, en que se aprobó la ley de propiedad horizontal (the Commonhold Act was passed) no existió en Reino Unido una regulación específica de la misma. Tengamos en cuenta que la mayor parte de los ciudadanos británicos viven en casas, no en pisos; pero no es menos cierto que también existen los bloques de viviendas. Esto se regulaba a través de la figura del leasehold. Aparentemente lo que sucede es lo siguiente: el dueño de un terreno que decide construir en él un bloque de pisos (a block of flats) continúa siendo dueño de la superficie, del terreno (ground) y otorga (grants) los leaseholds sobre los pisos por periodos que frecuentemente son de 99 ó 999 años, cobrando a los leaseholders una cantidad por el mantenimiento de las zonas comunes (communal areas) y a veces una renta por el terreno (a ground rent). La explicación más sencilla que podemos encontrar y dar es que el leasehold y el freehold se diferencian fundamentalmente en que el primero tiene siempre un límite temporal (is limited in time), más o menos extenso como vemos. Desconocemos la implantación y penetración que haya podido tener la Commonhold Act de cara a regular la propiedad horizontal. (..).
(…)


--------------------------------------------------
Note added at 3 hrs (2016-03-20 00:41:35 GMT)
--------------------------------------------------

Current situation in Northern Ireland:
http://www.housingadviceni.org/leaseholders-freeholders-and-...

The freeholder and the lease
The freeholder is the person who owns the land that your property sits on. This could be an individual or a company. The freeholder can sell the freehold to another person or company. You have a right to know who owns the freehold of your property.
The lease is the legal contract between you and the freeholder. When you’re buying a property it’s important that you have your solicitor examine the lease agreement to find out
• who the freeholder is
• if there are any specific terms which you have to agree with
• whether you need the freeholder’s permission to do certain things with the property
• how much your annual ground rent will be.
Your solicitor should also ask for confirmation that the ground rent account is up to date. Any problems with the lease need to be sorted out before the sale completes.
Ground rent
You will normally have to pay ground rent to your freeholder. This will be an annual charge. The lease should say when and how this charge can be increased. If you don’t pay your ground rent, the freeholder can take you to court to get a court order requiring you to pay what is owed.
You might also have to pay a service charge on top of the ground rent, particularly if you live in a communal apartment block. At the moment there is no regulation of service charges in Northern Ireland.


--------------------------------------------------
Note added at 1 day16 hrs (2016-03-21 13:15:10 GMT) Post-grading
--------------------------------------------------

Jaquelina: I am really glad that I could help :-) Please consider if this translation suggestion in worth being entered into the KOG-glossary for future reference. You have the full context (I don´t) and are therefore in a better position to judge. Kind regards, Toni.