No, once you’re assigned a NISS, it remains the same for life. It doesn’t require periodic renewal. Related ArticlesWhy do you need a NISS in Portugal?What documents do I need to apply for a NIF?How to correct/update your name on Portal das FinançasDo I need a tax representative in Portugal if I'm an EU/EEA resident?If I get a NIF from Novomove, does that mean I have to start filing taxes in Portugal?