Besides three months of arrears, the landlord may terminate when the tenant is more than eight days late in paying rent on more than four occasions, consecutive or not, within a 12-month period.
But paragraph 6 of the same article imposes a condition: the landlord may only terminate on this ground if, after the third late payment, they informed the tenant by registered letter with acknowledgement of receipt of their intention to end the lease on those terms.
It is easy to forget and impossible to fix afterwards. A landlord who did not send the letter after the third lateness cannot rely on this ground.
Keep the acknowledgement of receipt. It is the proof that the requirement was met.
Source：https://www.pgdlisboa.pt/leis/lei_mostra_articulado.php?nid=775&tabela=leis
This text is a summary of the law and does not constitute legal advice. For your specific situation, consult a lawyer admitted in Portugal.
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