Whether or not you're currently in a relationship, there's a good chance that your second act could be a solo one. Some 36% of women and 19% of men over age 65 live alone, according to a 2014 Census Bureau report.

Of course, whether or not you have a partner, the usual planning basics apply: You need to save diligently, invest in a diversified portfolio, and maintain an emergency fund.

Yet people who are single face additional challenges compared to their married peers. Among workers, 31% of unmarried men and just 19% of unmarried women say they feel very confident about their financial aspects in retirement, according to the 2016 Retirement Confidence Survey by the Employee Benefit Research Institute and Greenwald & Associates. And solo retirees are likely to confront specific hurdles, depending on whether they are divorced, recently widowed or simply don’t have a long-term partner. Here are some key considerations for each of those three situations:

When you're newly divorced

So-called “gray divorces” are more commonplace nowadays: A quarter of new divorcees in the U.S. are 50 or older, according to 2013 research from Bowling Green State University. When a marriage ends as you're approaching retirement, you may face the possibility of lower savings, higher expenses or a smaller income-or some combination of these.

For example, splitting from your partner may leave you with a larger housing payment-or require you to sell your home or other property. You might have to fork over a portion of your income or your retirement savings to your ex. Any of these issues could get your solo plan off to a rocky start. Some steps to take:

Revisit your savings and your timeline. Recalculate your retirement income based on the amount in your own accounts (especially if you’ve split them with your ex). Then add in your expected Social Security benefits: If you are age 62, unmarried and divorced from someone entitled to Social Security retirement or disability benefits, you may be eligible to receive benefits based on his or her record. You may not realize that even if your ex-spouse passes away, you may also be eligible to claim a widow/widower’s benefit as early as age 60 if you are not disabled.

Now a hard question: Do you need to reconsider the age at which you'd planned to retire? Run the numbers again based on a later retirement age. You might be surprised by how much your savings can increase if you work just a bit longer.

Do a portfolio review. The stock/bond mix you created with your spouse may prove too aggressive or conservative for your solo savings goals-or for your personal risk tolerance. Now is a good time to bring these questions to the attention of a financial professional who can help you reassess your investment strategy based on your new circumstances.

A final note: Now that you're single you'll probably need to change beneficiaries on your retirement and brokerage accounts, and revise your estate plan.

If you've lost your spouse or partner

Like a divorce, bereavement typically entails adjustments on many fronts-but the grieving process (or the suddenness of the loss) can make managing a solo retirement even more complicated. The key issue here is managing both the emotional and financial demands of this transition.

Get help. There are multiple tasks when you have to reconfigure your future plans, but don't expect to handle them all yourself, given all that's at stake. You may want input from:

• An attorney who can help with the probate process and your estate plan.
• A CPA who can help you manage taxes.
• A financial advisor who can help you assess everything from your portfolio allocation to how your goals may change (for example, your shared dream of retiring abroad may not appeal to you now).

Postpone big decisions. If you've received a lump-sum payout from life insurance or a retirement plan or pension, put the money in a high-yield savings account for the time being. Don't make any major money decisions for at least six months. Instead, focus on the next steps, like filing the appropriate paperwork and managing your day-to-day expenses.

Take stock. Besides life insurance and your spouse’s 401(k) or IRA, you may be eligible to receive Social Security survivor benefits provided you were married for at least one year, in most cases. A divorced spouse must have been married 10 years to be eligible for an ex-spouse’s benefits. If you’ve inherited retirement funds, it may make sense to roll them over into your own tax-advantaged account.

When you've been single for a while

If you've been flying solo for some time, you've had the luxury of avoiding spousal squabbles about your plan. But longtime singles face specific hurdles around saving and having the right supports in place for the future.

Save more while you can. While married couples have the potential to save twice as much, they don't typically spend twice what singles do. Even though your 401(k) and IRAs have the same limits as anyone else’s, your lifestyle needs could cost proportionally more. Living expenses when you’re solo aren’t necessarily 50% of a couple’s, as many basic life expenses—such as rent or mortgage payments—may remain relatively constant. And some tasks previously performed by a partner, whether household chores, financial tasks or caregiving, could lead to extra expenses when you’re alone. So be sure to take advantage of savings vehicles available to you, such as an IRA or 401(k), and make sure your current savings are in sync with your retirement goals.

Put the right legal documents in place. If you don't have children or family that you trust to make financial decisions on your behalf, you must take steps to ensure that decisions about your health and money don't wind up being made by a court if you become incapacitated. You may want to designate a trusted friend to make those decisions for you; just make sure you discuss your wishes with him or her first. Have an attorney draw up a will that spells out which people or charities will receive your assets after you pass away, and make sure the executor of the will knows how to get access to your accounts and other critical documents.

Fill the necessary roles. You'll also want to name someone as your decision-maker for money and health needs via what's called a springing power of attorney and a springing durable power of health care, which only take effect in the event of incapacity, says Schwab’s Rob Williams.

You may also want to consider purchasing long-term care insurance. It's a big expense, particularly once you're in your 50s or 60s, but it's a smart option if you don't have loved ones who can care for you.