That seems to be a question that pops up during the initial application process, e.g., on the form that you submit if applying online.
I can't recall ever being in a position to specify that after I've joined a company. HR and payroll systems have always been preconfigured for me without issue, for instance.
So, as long as you didn't misrepresent it on your initial application materials, probably should just clear it up, OP—to be consistent. Although you're probably gonna be okay anyway if you don't (assuming you're not benefiting from it somehow).