United Airlines announced Monday that economy-class passengers will be charged $25 for checking a second bag on all domestic flights.

The charge will apply to passengers who purchased ticket on or after May 5.

This does not apply to frequent flyers, business or first-class travelers. Passengers who have andquot;premierandquot; status or higher in United's Mileage Plus program or andquot;silverandquot; status or higher with Star Alliance will still be able to check two bags for free.

Customers will also be charged a $100 flat fee per bag for up to four additional bags (previous prices were $85 to $125 per additional bag).

The change in baggage policy could generate $100 million annually for United, and company officials said the fee will help prevent higher ticket prices.