The temporary policy applies across all markets served by the airline and is aimed at giving travellers added flexibility when planning trips.
According to TAP, customers will still need to cover any fare difference or additional taxes if the original ticket class is unavailable at the time of rebooking.
The airline said flight changes must be made within the original validity period of the ticket and completed no later than seven days before the outbound flight.
TAP currently operates more than 1,250 flights each week to 88 destinations, including routes across Europe, North and South America, Africa, the Middle East, and Portugal.