The portal is open since 9 o'clock this morning.
Leaving Cert students wishing to do the written exam in November can now register to sit it.
The State Examinations Commission says it can be accessed on the Calculated Grades Student Portal.
Students have until 5pm on Friday to apply to sit the written exams, which will run from Monday the 16th of November to Friday the 11th of December.
Guidance Counsellor in Colaiste Mhuire CBS Mullingar Betty McLaughlin says they will take place outside of school hours: