- Flat Fee -- The first is to make it affordable to just about everybody so that all members pay the same amount. Then, because this will not cover all expenses, additional fundraising campaigns are required. We're all familiar with these types of fundraisers -- dinners, journals, chinese auctions, selling honors, etc.
- Discounted Fees -- The other type is to have high dues and then to offer discounts and lower levels of membership to people who cannot afford the full dues. This doesn't exempt the members from further fundraisers but it makes those campaigns less urgent.
- Service-Based Fee -- The third is that there are no membership dues per se but attendees are expected to pay for each service they receive, e.g. a seat, an honor, etc.
II. Collecting Money for the Temple
This past week's Torah reading began with the mitzvah of machatzis ha-shekel, donating half a shekel to the construction of the mishkan (Tabernacle). It is deduced from here (in various ways; see the introduction to the Artscroll Mishnah Shekalim) that there is a mitzvah for every adult male to contribute a half-shekel to the Tabernacle/Temple every year.
You might have thought that the Temple would have allowed for an unlimited donation with a minimum of a half-shekel, but that is not exactly the case. The Torah is explicit: "The rich shall not give more and the poor shall not give less than half a shekel" (Ex. 30:15). Every Jew must give the same amount. Historical accounts tell us that during the times of the Second Temple this was done by Jews around the world.
The question, though, is why this is the case. To answer this, we have to ask the inverse question. Why does the Torah need to tell us that the rich can't give more and the poor can't give less? The stated reason for this donation is to count the Jewish people by counting the number of half-shekel donations (Ex. 30:12). If people give more or less, then the count will not work.
III. Equal Donations
The Torah Temimah (Ex. ch. 30 n. 30) explains that rich people could, in theory, subsidize poor people so that, overall, they give the appropriate amount. For example, one rich person could give 4 shekel and nine poor people could each give 1/9 shekel so that overall 5 shekel are given for ten people. Therefore, the Torah tells us that despite this possibility, everyone should still give the same amount -- a half-shekel (cf. Pardes Yosef, Ex. 30:15).
I think that the reason for this can be looked at in two ways. On the one hand, every Jew is equally obligated in the communal responsibility of enabling the sacrificial service in the Temple (and Tabernacle) to function. A rich person is no more obligated in having a functioning community than anyone else. This equal obligation leads directly to paying equal amounts.
From the other perspective, every Jew has the same portion in the community's worship of God. A rich person is not closer to God and does not have any greater part in the communal service than someone less wealthy. That is why he gives the same amount as everyone else.
It is true that there are other opportunities for a rich person to contribute. There are optional sacrifices -- nedarim and nedavos -- that a rich person can choose to offer. There is also a method of donating any object, not just animals for sacrificing, to the Temple by sanctifying it to the bedek ha-bayis, which helps with the upkeep of the Temple. However, the core functions of the Temple were paid for by a superfund that collected the exact same amount from every Jew. I find that to be a very powerful message.
IV. Synagogue Applications
Moving to more recent times, the Shulchan Arukh (Orach Chaim 53:23) records a debate over how a community should raise funds to pay for a chazzan, the leader of services. The Shulchan Arukh follows the Rashba, that a tax should be levied on the community members based on each individual's wealth. However, the Rema states that the custom follows Rav Hai Gaon, who ruled that a community should levy half (or a portion) of the tax on a flat basis (each person pays the same) and the rest based on wealth. This is because the actual communal obligation for a chazzan is minimal -- a person who can pray in public, and just for those prayers. However, most communities hire someone with a beautiful voice and add other obligations -- weddings, funerals, etc. -- to his job requirements. The basic communal obligations that mirror the core functions in the Temple should be based on a flat tax like the half-shekel, while the additional job requirements should be paid for by a tax based on wealth.
Taking this to contemporary times, it would seem that it depends on the synagogue. Some synagogues provide only core functions -- prayer services; others provide additional more -- Torah lectures; and others go part way or all the way to full community centers with classes, sports activities, childcare and much more. It would seem that based on the Rema, core functions should be paid by all members while additional activities should be charged to members based on their ability to pay. To me, this means that synagogues should have a single membership fee and then raise additional funds from members differently. Or, they should have a minimum membership fee and allow/require people who can, to pay more. Either way, the first two models we described both fall under this approach.
I hesitantly suggest that the third model -- charging fees for services that people will choose to use based on their ability to pay -- is improper. However, it could be argued that certain services are universally required so this model translates into the second model -- a minimum fee with additional optional dues.
Regardless, more recent commentators point out that, clearly for financial reasons, the custom described by the Rema is no longer followed. Instead, membership is paid from a general communal that is collected solely based on wealth (see, for example, Aruch Ha-Shulkhan, Orach Chaim 53:23). It seems to me that this means that today, whatever works to keep your synagogue functioning is acceptable.