FCL.945 Obligations for instructors
Upon completion of the training flight for the revalidation of an SEP or TMG class rating in accordance
with FCL.740.A (b)(1) and only in the event of fulfilment of all the other revalidation criteria required
by FCL.740.A (b)(1) the instructor shall endorse the applicant's licence with the new expiry date of the
rating or certificate, if specifically authorised for that purpose by the competent authority responsible
for the applicant's licence.
So unless the IAA have specifically authorised it, you cannot sign!