While automatic IRAs could have a significant impact on retirement readiness if they became universal, just how significant that impact might be would depend on several factors.

That's according to new research from the Employee Benefit Research Institute (EBRI), which said that three major factors have to be considered when determining the effects of a universal auto-IRA plan:

• age

• default contribution rate

• opt-out rate (the percentage of eligible employees who choose not to participate)

IRAs were designed to help people who don't have an employer-sponsored retirement plan, particularly those who work at small companies, put money away for retirement in a tax-deferred account. However, most people who don't have a retirement plan at work also don't have an IRA.

There's been discussion about the possibility of proposed legislation that would obligate employers without retirement plans to be required to automatically invest a specific amount of employees' pay into an IRA, via a payroll deduction, unless the employee changes the arrangement or opts out.