For individuals the accumulation process for retirement purpose has a number of options. Each has an annual contribution level. It is prudent to plan withdraws in retirement with the best outcome.

401K Plans are used at companies and often times a company will match an employees contribution to a certain level using pretax dollars. These contributions are taxed when withdrawn

IRAs are used by individuals as an accumulation option also using pretax dollars. This is also used when an employee leaves a company and rolls over their 401K account from the employer plan to their individual account. These contributions are taxed when withdrawn.

A ROTH is another accumulation option but uses after tax dollars for accumulation. - Contributions are able to be withdrawn tax free because they are made of nondeductible contributions.