Date: October 04, 2017 04:55PM
I don't know how this works outside of the United States, but WITHIN the United States...
Jewish congregations are run by a Board of Directors, each of whom is elected by the members of that congregation.
The Board is in administrative charge of everything which concerns that congregation (which includes, but is not limited to, that group's finances). They hire (and, if necessary, fire) all of the salaried employees of the congregation (including the rabbi or rabbis, the cantors (ritual singers), and the staff (secretaries/clerks, janitorial staff, etc.).
All major financial decisions are ultimately made by the Board of Directors (often after considerable discussions with the general members, especially for the major, or the sensitive, issues). The rabbi (who is, administratively, a hired employee) would have a voice in these decisions, but does not make the decision...the Board of Directors does.
Certainly any member of the Board of Directors would have access to all the financial records, but probably so would any member who was interested...
...though there might be some exceptions to this in unusual or unique circumstances...such as the confidentiality surrounding a major real estate purchase.
I can think of one instance that falls into this category, to such an extent that it ultimately became the subject of a general audience (primarily non-Jewish readers) book, which sold a great many copies to Jews and non-Jews alike. This particular situation is still vividly remembered among Jews, and among a great many non-Jews as well. (It became a cautionary tale, whose very serious lessons were of general American interest, which took place in the community I grew up in. I drive by the once-proposed real estate in question several times a week, and as I drive by I still wonder what (financially) happened to the families who, in the 1990s as I remember, made the choice to become part of that situation.)