If your state doesn't have a usury law, then there is no maximum, much like when credit cards can charge such high rates.  The reason credit card companies can charge such high interest rates is because the contract when you agree to the card is based on the law where the card company is, not where you live. This is why many are located in places like Nevada or Delaware. So if you determine there is an interest rate cap in the state in which the private country club is located, you need to see how the contract is written and if the formulas in the contract will go above that maximum interest rate.  In New York, the legal rate of interest is something like 9 or 10 percent; but the usury limit is below 20% (I think it is somewhere like 16% or 17%).  Verify this amount and then review your contract.  If this is a privately owned company, the usury laws may still apply under your state's consumer protection laws.  Contact your local consumer protection agency (local prosecutor's office for the city or town or even the county) and file a complaint.  As far as tax laws, you need to determine what type of contract this is (service or otherwise) and whether your state allows for certain types of taxes.