Tax Plan Answers is a left-leaning tax policy advocacy organization. The group is a project of the Sixteen Thirty Fund, a funding and fiscal sponsorship organization for left-progressive lobbying projects managed by the Washington, D.C.-based consultancy Arabella Advisors. 
Tax Plan Answers is a project of the left-of-center lobbying and electoral organization Sixteen Thirty Fund, which critics have identified as a “dark money” front for liberal and Democratic electoral interests. 
The website ostensibly answers tax questions people have about the 2017 tax changes and presents left-progressive and Democratic Party talking points opposing the legislation.  For example, the website claims that while some modest earners may initially receive a tax cut, the website then claims that by 2027, 53% of Americans will pay more taxes because of the law. 
The organization also claimed that since the law eliminated the requirement to purchase insurance, about 13 million fewer people will purchase health insurance and that health insurance “may rise by an additional 10% each year.” 
The Sixteen Third Fund is a left-of-center lobbying and advocacy organization founded in 2008.  Sixteen Thirty Fund often operates alongside its charitable “sister” nonprofit New Venture Fund, which provides similar funding and fiscal sponsorship services to center-left organizations.  According to its founding documents, the Sixteen Thirty Fund was created with seed funding from Americans United for Change (AUFC), ACORN, USAction, the Sierra Club, and Working America. 
Arabella Advisors (commonly called “Arabella”) is a philanthropic consulting company that guides the strategy, advocacy, impact investing, and management for multiple left-leaning nonprofits and individuals.  The company was founded in 2005 by Eric Kessler, a Clinton administration alumnus and long-time staffer at the League of Conservation Voters who remains a senior managing partner at the firm. 
Arabella Advisors manages four nonprofits that serve as incubators and accelerators for a range of other left-of-center nonprofits. These include the New Venture Fund, the Sixteen Thirty Fund, the Hopewell Fund, and the Windward Fund. These nonprofits have collectively hosted hundreds of left-wing policy and advocacy organizations (referred to by critics as “pop-up groups” because they are often little more than web sites). In 2018, Arabella’s four nonprofits reported combined revenues of $635 million.