(CNN) — Spirit Airlines customers will soon need to plan ahead to save money.

Starting November sixth, the carrier will charge a $100 fee if passengers need to check their carry-on baggage at the gate.

The airline says the fee is intentionally high, to discourage fliers to wait until the last minute.

Spirit charges for all bags that do not fit underneath a seat.

Spirit says fliers checking bags in advance can pay as little $20 a bag.