BOSTON (TheStreet) -- Vanguard has launched an online service enabling investors to compare and buy annuity product offerings from a number of insurance companies.Vanguard Annuity Access, which went live Wednesday, is targeted to "self-directed" people seeking a postretirement income stream to augment their investment holdings, workplace retirement plan and Social Security benefits. Prospective buyers can get customized quotes for income annuities, evaluating comparable contracts from multiple companies. It will also offer access to fixed deferred annuities with fixed interest durations ranging from three to seven years. These savings vehicles are designed for tax-sensitive investors wishing to supplement other forms of retirement savings, such as 401(k) plans and IRAs. A fixed deferred annuity lets clients earn a fixed interest rate on their savings for a set number of years. The interest rate and principal are guaranteed by the insurance company that issues the annuity. The service is a partnership between Vanguard and Hueler, a provider of web-based annuity purchase systems. Vanguard provides recordkeeping and investment services for more than 2,500 defined contribution plans. According to the announcement, participants can use Vanguard Annuity Access as an IRA rollover option. The approach allows plan sponsors to avoid the added fiduciary responsibility and increased plan complexity of "in-plan" options. Having comparison tools available is important because income annuity products may not be advisable for everyone, says John Ameriks, head of Vanguard Investment Counseling & Research. Potential downsides include loss of investment liquidity, the potential reduction in bequeathable wealth and the risk of default of the underlying insurer. "For retirees who place a high value on having an additional lifetime income guarantee beyond Social Security and a pension -- and are willing to accept the costs and risks of annuitization -- low-cost income annuities can be an important part of a broader investment plan," he says. --Written by Joe Mont in Boston. >To contact the writer of this article, click here: Joe Mont. >To follow the writer on Twitter, go to http://twitter.com/josephmont. >To submit a news tip, send an email to: firstname.lastname@example.org.