Big Tech Accountability for Broadband Act This bill requires the Federal Communications Commission (FCC) to promulgate regulations requiring covered businesses to contribute to the federal universal service support mechanism. A covered business is a business offering an online platform (e.g., a social media platform) that has (1) more than 30 million U.S. users or 300 million worldwide users, and (2) more than $10 billion in global revenue. The federal universal service support mechanism collects money from telecommunications companies and uses it to expand broadband access and infrastructure, especially in unserved and underserved areas. In promulgating such regulations, the FCC must consider including a mechanism that prohibits a telecommunications carrier from requiring a customer to pay charges related to universal service support contributions if the customer is considered unserved or underserved with respect to broadband internet access.