Treasury Secretary Janet Yellen said a shocking" amount of taxes was going uncollected by the federal government. "The gap between what we're collecting in taxes on current tax and what we should be collecting ... amounts to over $7 trillion over a decade," Yellen said. Yellen's remarks emphasize the Biden administration's efforts to collect tax revenue from the wealthiest Americans and multinational companies to finance $4 trillion in spending programs. At the center of Biden's planned revenue raisers is a provision to increase funding for IRS enforcement. He also wants to slap investors earning above $1 million with a hike in the capital-gains tax and raise the top marginal income-tax rate to 39.6% from 37%. The IRS's official estimate is that there is a tax gap of $441 billion a year. But Charles Rettig, the agency's commissioner, recently told Congress that number could be over $1 trillion. A recent study from IRS researchers and academics found that the top 1% of Americans failed to report about one-quarter of their income to the IRS. The research found income underreporting was nearly twice as high for the top 0.1%, which could account for billions in uncollected taxes. The number of agents devoted to working on sophisticated tax-evasion enforcement dropped by 35% over the past decade. The IRS's budget fell by 20% between 2010 and 2018. There was an 80% decline from 2011 to 2018 in the audit rate for those making over $1 million a year.