You register on SEF website with your email, date of birth, and document number (residence title, residence card). After receiving a confirmation email, you login and then go to requests - automatic renewal. You enter your password, residence permit number and it takes you to a pre-filled page with your data. The data is: Residence Permit Number, Name, Surname, Marital Status, NIF number then address to receive the card. When you double check this data and confirm, it sends you an automatic email with the payment amount and reference number. In the email it mentions that the payment will be possible within 48 hours. There are no documents needed to upload or anything. Very straightforward and easy renewal.