I am a member of a Shul and am behind with my payments. Being behind makes me a non-financial member and limits my rights. The Shul board has decided to charge an extra 20% men mikva fees for non-financial members. Is it a problem of ribis?
The stipulation of two different prices only involves a prohibition of ribis when there is a difference in the method of payment: the more expensive price is charged for credit payments, and the cheaper price for cash up front. The charging of two prices, one for financial members and one for non-financial members, does not constitute a problem.
Because there is no basic problem in having two rates, it follows that there is no prohibition even in your personal case. Although you owe a ‘debt’ to the shul, the extra charge is not being taken as a payment of interest on the loan, but as a general rate for non-financial members. The fact that you are considered a non-financial member on account of your being behind in payments does not mean that the charge is being taken as interest.
In addition, it should be noted that your ‘debt’ might not constitute a chov with respect to ribis, because you never ‘borrowed’ money from the shul; furthermore the shul might not be comparable to a regular individual to whom the laws of ribis apply. There is much to write concerning these last two factors, but under the specific circumstances there is no need to elaborate on them.