The ONSS is inflexible in case of late DIMONA for student

Not introducing a “student” Dimona statement on time, will cost you.
Late hours of work are not earmarked for the 475-hour student quota.
Ordinary ONSS contributions are deducted from the remuneration granted for these hours.
The Dimona declaration must be submitted no later than the first day of the relevant work period.

Source: Paterna professional