Building codes change over time and some homes built prior to the implementation of the current IRC egress window code will not be up to date. If you are doing a renovation of your basement, you will have to meet the current egress window code, even if the windows that were previously in place did not meet code.
However, if you are not doing any renovations, you will not be required to update your basement windows. Homes built before the IRC was implemented have their current windows “grandfathered” in.