…from:
http://www.apple.com/support/usbc-chargecable/


Apple USB-C Charge Cable Replacement Program 

A limited number of Apple USB-C charge cables that were included with MacBook computers through June 2015 may fail due to a design issue. As a result, your MacBook may not charge or only charge intermittently when it’s connected to a power adapter with an affected cable.

Apple will provide a new, redesigned USB-C charge cable, free of charge, to all eligible customers. This program also covers Apple USB-C charge cables that were sold as a standalone accessory.

For MacBook owners who provided a valid mailing address during the product registration process or Apple Online Store purchase, Apple will send you a new cable by the end of February 2016.

All other eligible MacBook owners should use the replacement process below to receive a new USB-C charge cable.

Identifying an affected cable

Affected cables have “Designed by Apple in California. Assembled in China.” stamped on them. New, redesigned cables include a serial number after that text. See images below.

Affected cable Affected cable detail
Redesigned cable Redesigned cable detail

Replacement Process

Please choose one of the options below to receive a new USB-C charge cable. We will need your MacBook serial number to verify eligibility for this program. Learn how to find your serial number here


Additional Information

This worldwide Apple program does not extend the standard warranty coverage of the MacBook.

If you believe you have paid for a replacement due to this issue, contact Apple regarding a refund.

The program covers the affected USB-C charge cables until June 8, 2018.

Information as of 2016-02-12