Thinking of buying a used car? It could have implications for the IUC (Single Circulation Tax). When buying a car, attention is usually focused on price, fuel consumption, insurance, and in many cases, the monthly payment. But there's an annual charge that still goes unnoticed by many Portuguese: the IUC, the Single Circulation Tax. Although it's a mandatory expense for car owners, the amount to pay varies depending on several factors, such as the license plate, engine size, and the vehicle's CO2 emissions. In practice, this means that two seemingly similar cars can represent quite different annual costs for the family budget. This is precisely why the topic has gained relevance among those considering buying a car, especially in the used market. In a context where every euro counts, understanding the real cost of owning a car has ceased to be just a matter of comparing sale prices and now includes recurring expenses like maintenance, fuel, insurance, and taxes. To help consumers do the math before making a final decision, ComparaJá launched an IUC calculator, a tool that allows simulating the value of this tax simply. The goal is to provide more transparency to an expense that often arises too late in the purchase process, when the deal is already closed. The tool can be useful for those comparing various options in the automotive market and want to understand which one will have the least annual impact on their budget. Instead of discovering the tax value only after acquisition, the consumer can anticipate this cost and integrate it into a more comprehensive analysis. This approach becomes even more important at a time when many drivers are looking for ways to reduce fixed charges. A car with a more attractive purchase price may, after all, translate into a heavier annual bill when the IUC and other associated expenses are taken into account.