Passport offices in Dublin and Cork will be hit by industrial action today.
Anyone who has already arranged to collect their passport must do so by 1pm this afternoon.
The Department of Foreign Affairs has confirmed that the public counters in Cork and Dublin will not be operating normally today.
It comes as staff escalate their campaign against cuts in public service pay.
The action has already affected the phone services.
It won't be possible for the offices to accept further passport applications for collection before 2.30pm on Monday - applications or deliveries made by mail or through the Passport Express Service are not affected.
The Department said it cannot guarantee the turnaround time for its passport services and is apologising for the inconvenience.