Since March 16th, and until April 15th is running the deadline to file the 2017 Human Resource Return (“Relatório Único”), as provided in Ordinance 55/2010, of 21 January.
The Return has 5 Annexes that can be filled individually once they are completed (within the deadline) with no specific priority, eg Annex A before Annex B.
You can check the link for issues related to the delivery of the single report.