Data show that roughly 70 million workers participate in an employer-sponsored 401(k) plan as a key retirement savings vehicle, and 401(k) matches offered by many employers help boost those savings each year. A Vanguard How America Saves report estimates the average employer match in the United States at about 4.6% of pay, in addition to employees' own contributions. For someone earning $75,000 a year, that amounts to roughly $3,450 in additional tax-advantaged retirement savings annually. Some workers consider this effectively "free money" on top of their regular pay. From just $107.88 $24.99 for Kiplinger Personal Finance Become a smarter, better informed investor. Subscribe from just $107.88 $24.99, plus get up to 4 Special Issues CLICK FOR FREE ISSUE Sign up for Kiplinger’s Free Newsletters Profit and prosper with the best of expert advice on investing, taxes, retirement, personal finance and more - straight to your e-mail. Profit and prosper with the best of expert advice - straight to your e-mail.…