Spirit Airlines said it will begin charging passengers $30 for each carry-on bag that needs to be stored in an overhead bin. The fee applies to travel starting Aug. 1.

Passengers will not be charged for items that can be stored underneath the seat.

The $30 fee can be paid in advance, either online or over the phone, or at airport check-in.

Customers who belong to Spirit’s $9 Fare Club will get a discount, paying $20 for carry-on bags if they pay in advance online. (According to Spirit’s website, membership in the $9 Fare Club costs $39.95 per year.)

Flyers who pay the fee in advance will receive priority boarding in Zone 1.

All passengers who pay for a carry-on bag at the gate will be charged $45, and cash won’t be accepted, according to Spirit.

Exceptions to the fee for carry-on bags are umbrellas, assistive devices, outer garments (coats, hats, wraps), cameras, car seats/strollers, infant diaper bags, medicine, pet containers, reading materials for the flight or food for immediate consumption.

Also effective Aug. 1, Spirit will reduce checked-bag fees for $9 Fare Club members: $15 for domestic flights and $20 for international flights, a $10 savings. To get the discount, $9 Fare Club members must pay in advance at Spirit’s website.

Checked-bag discounts and the new fee for carry-on bags will be available for purchase by July 1, said Spirit.