Delivery slowdowns at the U.S. Postal Service take effect Friday, and higher prices are soon to follow. The nation’s mail service is preparing to implement core components of Postmaster General Louis DeJoy’s 10-year plan for the agency, a program designed to cut costs and raise new revenue to fix its many financial problems.

The Postal Service has struggled for years with financial losses due to declining mail use, and the coronavirus pandemic exposed more issues within the agency as it struggled to cope with an avalanche of e-commerce purchases, worker availability problems and a disorganized processing network.

DeJoy, the controversial Trump ally who took over the agency months before the 2020 presidential election, introduced his vision for the agency in March with the backing of the Postal Service’s bipartisan governing board. A major component of that plan — slower service — is set to kick in.

Here’s everything you need to know about the changes at the Postal Service.