"You look at the $18,000 and wonder, gee, how many people can practically get to that level?" Joe Ready, director of Wells Fargo Institutional Retirement and Trust, told CNBC. But as people "progress in their careers and earnings progressively go up," it will be increasingly important for elderly investors to max out the $24,000 limit, he said.

The AARP, in its coverage of the news, said that though workers will be permitted to save more in their 401(k) or similar workplace plan, "it's likely that most of them won't take advantage of it, given that they don't max out contributions now."

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The organization cited a recent report by the Center for Retirement Research at Boston College that noted that only 12 percent of participants in 401(k)s administered by fund giant Vanguard put away the maximum amount. And those most likely to contribute the maximum earned at least six figures.

Along those lines, Wells Fargo on Wednesday released the findings of its fifth-annual Middle Class Retirement Survey, which concluded that more than a third of middle-class families aren't saving anything in a 401(k), IRA or other vehicle. For those 50 to 59 years old, the number jumps to 41 percent. 

"Nearly a third (31 percent) of all respondents say they will not have enough money to 'survive' on in retirement," the bank said. "This increases to nearly half (48 percent) of middle-class Americans in their 50s."

Those sort of statistics have spurred calls for all kinds of reform of the private-sector retirement system, including proposals to lift contributions limits even higher. Some hope that Congress might act next year, taking action on tax legislation that might include such provisions. On the other hand, the industry is also concerned that lawmakers will cut some of the tax benefits in retirement savings programs.

On Thursday, the IRS did more than raise the limits for individuals.

It also raised the limit on annual maximum contributions to SEP IRAs and solo 401(k) plans for the self-employed and small-business owners to $53,000 in 2015, up from $52,000. The amount that can be contributed is based on a percentage of maximum salary, which has been increased to $265,000, up from $260,000.

The limit on defined benefit annual pensions will remain unchanged next year, at $210,000.

Contributions to SIMPLE defined contribution plans, which require employers to make a minimum contribution to participants' accounts, will increase to $12,500, up from $12,000.

The COLA increases will not extend to IRA contributions. The $5,500 annual limit will remain the same, as will the $1,000 limit for catch-up contributions. But IRA investors will see increased tax benefits in 2015. Deductions for traditional IRA contributions for individuals and couples who also participate in employer sponsored defined contribution plans will be phased out once adjusted gross income falls between $61,000 and $71,000. That is a $1,000 increase from last year.

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For married couples filing joint tax returns, the IRA deduction phases out when AGI falls between $98,000 and $118,000, when the contributing spouse is also a participant in an employer-sponsored plan. That is an increase of $2,000 for the previous year.

Those traditional IRA contributors not covered by a workplace plan, but whose spouses are, will have their deduction phased out when the couple's AGI reaches $183,000 to $193,000, also an increase of $2,000.

The AGI phase-out range for Roth IRAs will also see COLA changes in 2015, increasing to $183,000 to $193,000 for married couples filing jointly. Singles and heads of households will see the phase-out range increase to $116,000 to $131,000, up $2,000 from last year.

The "savers credit," the tax incentive for lower and moderate-income savers, also will increase in 2015.

The AGI limit for married couples filing jointly will be $61,000 in 2015, up from $60,000; $45,750 for heads of households, up from $45,000; and $30,500 for married individuals filing separately and for singles, up from $30,000.

Contribution limits are tied to inflation and are reviewed by the IRS each year. Last year, the Consumer Price Index had not climbed enough to trigger an increase in the limits.

Click here for more details on the IRS website.