For the People Act of 2021 This bill addresses voter access, election integrity and security, campaign finance, and ethics for the three branches of government. Specifically, the bill expands voter registration (e.g., automatic and same-day registration) and voting access (e.g., vote-by-mail and early voting). It also limits removing voters from voter rolls. The bill requires states to establish independent redistricting commissions to carry out congressional redistricting. Additionally, the bill sets forth provisions related to election security, including sharing intelligence information with state election officials, supporting states in securing their election systems, developing a national strategy to protect U.S. democratic institutions, establishing in the legislative branch the National Commission to Protect United States Democratic Institutions, and other provisions to improve the cybersecurity of election systems. Further, the bill addresses campaign finance, including by expanding the prohibition on campaign spending by foreign nationals, requiring additional disclosure of campaign-related fundraising and spending, requiring additional disclaimers regarding certain political advertising, and establishing an alternative campaign funding system for certain federal offices. The bill addresses ethics in all three branches of government, including by requiring a code of conduct for Supreme Court Justices, prohibiting Members of the House from serving on the board of a for-profit entity, and establishing additional conflict-of-interest and ethics provisions for federal employees and the White House. The bill requires the President, the Vice President, and certain candidates for those offices to disclose 10 years of tax returns.