Check up on Medicare
This year's Medicare open enrollment started on Oct. 15 runs through Dec. 7. During this period, people with Medicare—the federal government's health-insurance plan for those age 65 and older—can change their health plan or prescription-drug coverage for 2014.
(Read more: Will Medicare will run out in 2026?)
"It's a shorter window than it used to be," said retirement and Social Security expert Mary Beth Franklin, who is also a contributing editor at InvestmentNews, a business newspaper that covers the financial services industry.
"Those who are happy with their Medicare benefits don't have to change anything, but it's advisable for everyone to review what they have, because the plans themselves change year to year," she said.
Health-care costs consume a significant percentage of a retiree's budget, especially in later years. In fact, couples retiring in 2013 will need an estimated $220,000 to cover lifetime medical expenses, according to Fidelity Investments.
Therefore, it's important to use Medicare plans effectively. Franklin said retirees should pay special attention to their out-of-pocket prescription-drug costs. Depending on the types of medication they take, it may be less expensive to purchase Medicare Part D, which provides prescription drugs at a lower cost.
Likewise, financial advisors urge individuals to crunch the numbers to determine whether they would benefit financially by opting for Medicare Advantage (Part C) instead of traditional Medicare plus Parts A and B, or by choosing supplemental coverage through Medigap, which may lower their deductibles and copays.
Appraise a taxing development
Retirees who would normally fall into the low- to middle-income tax brackets may also get an unwelcome surprise this year when they find they are potentially subject to a 3.8 percent Medicare surtax reserved for higher-income earners.
The surtax, new in 2013, applies to net investment income for married taxpayers with modified adjusted gross income (MAGI) above $250,000, and single filers with MAGI above $200,000.
Retirees who experience a one-time windfall, however, from the sale of their business or highly appreciated primary residence could easily meet the income threshold, said Phil Cook, a certified financial planner with Cook and Associates.
(Read more:Tax-planning checklist)
Proceeds from the sale of a principal residence, up to $500,000 for married filers and $250,000 for single filers, are excluded from capital-gains treatment.
However, any gain beyond that amount is not only taxed as a capital gain but is also subject, either in part or in full, to the additional 3.8 percent surtax if it pushes annual income over the threshold.
"We're trying to identify all of our clients right now who might be impacted," Cook said.
Income collected from pensions, qualified retirement plans, individual retirement accounts or 401(k) plans also contribute to an investor's annual net income.
These collectively can push someone over the surtax threshold, as well— particularly for those who withdraw a large sum to, for example, take their extended family on vacation or purchase a condo in Miami to escape winter weather.
A number of strategies, such as recharacterizing income and gifting appreciated assets, can help reduce taxable investment income for 2013, but most require financial expertise and all must be implemented by Dec. 31.