It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

The best way to shortlist great mutual funds is to ensure solid performance, diversification, and low fees. Some are better than others, but utilizing the Zacks Mutual Fund Rank, we have identified three mutual funds that could be solid additions to one's retirement portfolio.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

Heartland Value Fund Institutional (HNTVX Quick QuoteHNTVX - Free Report) : 0.91% expense ratio and 0.75% management fee. HNTVX is a Small Cap Value fund, and these funds are known for investing in companies with market caps under $2 billion. With annual returns of 15.6% over the last five years, this fund is a winner.

Neuberger Berman Social Responsible Institutional (NBSLX): 0.69% expense ratio and 0.64% management fee. NBSLX is a Large Cap Value fund. These funds invest in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. NBSLX, with annual returns of 17.21% over the last five years, is a well-diversified fund with a long track record of success.

Nuveen Core Equity A (TIIRX): 0.68% expense ratio and 0.39% management fee. TIIRX is a part of the Large Cap Growth mutual fund category, which invest in many large U.S. companies that are expected to grow much faster compared to other large-cap stocks. With a five-year annual return of 16.33%, this fund is a well-diversified fund with a long track record of success.

We hope that your investment advisor (if you use one) has you invested in one or all of the top-ranked mutual funds we've reviewed. But if that isn't the case, it might be time to have a conversation or reconsider this vitally important relationship.