In the United States, a 401(k) plan is an employer-sponsored, defined-contribution, personal pension (savings) account, as defined in subsection 401(k) of the U.S. Internal Revenue Code. Periodical employee contributions come directly out of their paychecks, and may be matched by the employer. This legal option is what makes 401(k) plans attractive to employees, and many employers offer this option to their (full-time) workers. There are two types: traditional and Roth 401(k). For Roth accounts, contributions and withdrawals have no impact on income tax. For traditional accounts, contributions may be deducted from taxable income and withdrawals are added to taxable income. There are limits to contributions, rules governing withdrawals and possible penalties. The benefit of the Roth account is from tax-free capital gains. The net benefit of the traditional account is the sum of (1) a possible bonus (or penalty) from withdrawals at tax rates lower (or higher) than at contribution, and (2) the impact on qualification for other income-tested programs from contributions and withdrawals reducing and adding to taxable income, minus the consequences of capital gains being taxed at regular income rates. As of 2019, 401(k) plans had US$6.4 trillion in assets. History Before 1974, a few U.S. employers had been giving their staff the option of receiving cash in lieu of an employer-paid contribution to their tax-qualified retirement plan accounts. The U.S. Congress banned new plans of this type in 1974, pending further study. After that study was completed, Congress reauthorized such plans, provided they satisfied certain special requirements. Congress did this by enacting Internal Revenue Code Section 401(k) as part of the Revenue Act. This occurred on November 6, 1978. The first implementation of the 401(k) plan was in 1978, about three weeks after Section 401(k) was enacted, before the Revenue Act of 1978 even went into effect. Ethan Lipsig, of the outside law firm for Hughes Aircraft Company, sent a letter to Hughes Aircraft outlining how it could convert its after-tax savings plan into a 401(k) plan. Ted Benna was among the first to establish a 401(k) plan, creating it at his own employer, the Johnson Companies (today doing business as Johnson Kendall & Johnson). At the time, employees could contribute 25% of their salary, up to $30,000 per year, to their employer's 401(k) plan. Taxation There are two main types corresponding to the same distinction in an Individual Retirement Account (IRA); variously referred to as traditional