Una derrama
 

Derrama is when after paying all building fees, there's still some extra payments to make. In Spanish we say, there is a derrama of 200 Euros for example.
English?

cost overrun

could u use it in context please?

It is used most often in finances of a communal complex of the kind found in Spain, but not in the UK, so there is no easy equivalent in BrE. I have often had to translate the word into English in that context, and the best I can think of is an apportionment. This is not very good, because not many English people have met the word.

The community funds were insufficient to cover the one-off cost of installation of a satellite disk, so the administrator was authorized to take one apportionment payment for the project.

Derrama
 

Derrama - apportionment / proportional assessment / proportional payment of an extraordinary expense.

Perhaps I'm misunderstanding something here, but unexpected additional
fees, the type that often incurr in building expenses, are known as
cost overruns in North American English. Apportionments must be a British
term.

A cost overrun assumes you had a budget for a specific project and you went over it. I'm not sure this is the case for this word in Spanish.

can you give me a sentence :
Se ruega a los Srs propietarios ingresen en la cuenta de la comunidad 200 euros de derrama.
Translate please.

It's requested that the gentlemen proprietors pitch in an additional 200
euros to the community chest to cover cost overruns.

Perfect. thank you very much !

If the project is a house we say se ha pasado de presupuesto.