money in the account. It is a "basic right that has been granted, or has accrued, and cannot be taken away"; for example. one has a right to a vested pension. Generally, the portion vested cannot be reclaimed by the employer, nor can it be used to satisfy the employer's debts. Any portion not vested may be forfeited under certain conditions, such as termination of employment. The portion invested is often determined pro-rata. Generally, for retirement plans in the United States, employees are fully vested in their own salary deferral contributions upon inception. For employer contributions, however, such as those from an employer matching program, the employer has limited options under the Employee Retirement Income Security Act (ERISA) to delay the vesting of their contributions to the employee. For example, the employer can say that the employee must work with the company for three years or they lose any employer contributed money, which is known as cliff vesting. Or it can choose to have the 20% of the contributions vest each year over five years, known as graduated vesting or graded vesting. Choosing a vesting schedule allows an employer to selectively reward employees who remain employed for a period of time. In theory, this allows the employer to make greater contributions than would otherwise be prudent, because the money they contribute on behalf of employees goes to the ones they most want to reward. Ownership in startup companies Small entrepreneurial companies (startups) usually offer grants of common stock or positions in an employee stock option plan to employees and other key participants such as contractors, board members, advisors and major vendors. To make the reward commensurate with the extent of contribution, encourage loyalty, and avoid spreading ownership widely among former participants, these grants are usually subject to vesting arrangements. Vesting of options is straightforward. The grantee receives an option to purchase a block of common stock, typically on commencement of employment, which vests over time. The option may be exercised at any time but only with respect to the vested portion. The entire option is lost if not exercised within a short period after the end of the employer relationship. The vesting operates simply by changing the status of the option over time from fully unexercisable to fully exercisable according to the vesting schedule. Common stock grants are similar in function but the mechanism is different. An employee, typically a