SEPs can be started by most employers, including those who are self-employed. Businesses are not locked into making contributions every year. Employers also may make profit-sharing contributions to a plan that are unrelated to any amounts an employee chooses to contribute. Many individuals eligible to contribute to an IRA do not. One reason is that some individuals wait until the end of the year to set aside the money and then find that they do not have sufficient funds to do so.
Payroll deductions allow individuals to plan ahead and save smaller amounts each pay period.
Payroll deduction contributions are tax-deductible by an individual to the same extent as other IRA contributions.