Pat Sterner, who runs her own business consulting for nonprofits in Duluth, Minn., would love to retire and spend more time kayaking on Lake Superior. In the summer, she says, her neighbors “are always knocking” on her door to get her out.

But even though she would like to take on fewer clients, she’s not quite ready to close shop. “My kids laugh and say, ‘Are you really retiring?’” said Ms. Sterner, 66. “It’s a little nerve-racking. I’d like to leave the door cracked open.”

Ms. Sterner’s concerns — about having enough money, leaving the business she built — mirror those of millions who are close, but not quite ready, for full-stop retirement.

For many, getting to retirement age is not a simple matter of giving two weeks’ notice. You may want to extend a career or wind down work life or a business. If you’re able, you may want to keep working until you are 70 (and beyond), when you will receive the largest possible Social Security payment.

These in-betweeners are slow-walk planning to arrive at the moment when they are not working anymore. What’s involved is a delicate jigsaw puzzle of decisions, nest egg bolstering and financial calculations. This transitory time also presents a meaningful time for reflection and short-term planning.

Roughly 55 million Americans are 65 and older now, with those born at the peak of the baby boom hitting that milestone age this year. As a combination of the pandemic, job dislocation, inflation and higher medical costs continues to sting retirees, millions are staying in the work force while they transition to full retirement. Whether you’ve already chosen your quit date or are mulling your options, there are several issues to consider.

Social Security Benefits

The age at which you take Social Security is crucial for tax and investment portfolio planning, so run some numbers on benefits at various ages. The good news is that you won’t be taxed with a Social Security “earnings penalty” if you’re working and take benefits on or after age 66½, which is, for most people, what the Social Security Administration calls the full retirement age. Of course, you can begin to draw benefits anytime after age 62, but the earlier you retire, the lower the monthly payment.

The administration looks backward at your best earnings years and forward to the age you’ll be taking them to calculate your monthly check. While many financial advisers counsel their clients to wait as long as they can to pull the Social Security trigger, only a handful do. Some 5 percent of people surveyed last year by the asset manager Schroders said they took Social Security at 70, when the highest possible benefit is paid. That often leaves a gap to fill.

Keep in mind that Social Security gets complicated when you’re considering spousal benefits, which generally are as much as half of the other beneficiary’s primary insurance amount, or the amount one would receive at full retirement age. You can apply for the spousal benefit beginning at 62, or you can wait to apply later for a higher benefit. It’s also possible to draw a higher payment based on your own lifetime earnings record. You’ll need to run some numbers to see how to best maximize payments. Divorced people, under certain circumstances, may also qualify for spousal benefits.

You also need to do some Medicare planning before you turn 65. There are a number of programs to know about, so spend some time on medicare.gov. Also note that Medicare premiums are tiered — there are six levels — and based on income: The more you make, the higher the premium. Your tax filing status also matters in the pricing.

Of course, none of the parts of Medicare provide 100 percent coverage, but you can buy Medicare supplemental insurance, known as Medigap, through private insurers. Premiums vary widely, depending on how much of your out-of-pocket expenses you want to cover, your age and whether you smoke. Medicare Advantage plans also may cover some out-of-pocket expenses.

At the very least, estimate your benefits and out-of-pocket insurance costs at various ages. You need to balance maximizing Social Security and tapping other savings to get to your desired hard-stop retirement date. Another key factor when doing Social Security planning: your health and longevity. Those who can wait to collect until 70 are typically in relatively good health and not faced with serious chronic illness.

“A strong consideration is your family history and longevity,” says Nicole Strbich, a certified financial planner with Buckingham Advisors in Dayton, Ohio. “We incorporate Medicare planning with clients as part of their retirement conversation. Understanding the timing needed to apply for benefits and the expected costs — the anticipated rate of inflation for those costs — and the increased costs for higher-income individuals, are important components of a retirement plan.”

A Phased Retreat

Once you’ve run some numbers on Social Security and Medicare, you can create a timeline. Your employer may even help you with “phased” retirement programs, in which you gradually reduce your hours until a certain year.

Responding to a long-running trend of employees working past age 65, these programs embrace those who are not ready to fully retire. Although the over-65 labor force participation rate changes from year to year, it’s around 19 percent, compared with a historical average of nearly 17 percent, according to Bureau of Labor Statistics data.

The reasons for delaying retirement are myriad. In many professions, improved longevity means being able to work longer. Many find meaning from work, so they want to continue. Others may need to save more as guaranteed defined-benefit pensions have become the exception and not the rule. Many workers simply want to take advantage of the additional amount of annual catch-up money they can save in 401(k)-style plans.

While phased retirement programs are increasingly desirable in the workplace, they are also rare. Only about 15 percent of employers offer some kind of phased retirement, with about 6 percent offering a formal program, according to the Society of Human Resources Management, although you may be able to negotiate a phased plan on your own.

Financing Your Way Out

Planning is essential. One of the first items Ms. Sterner in Minnesota reviewed with Sam Brownell, a chartered financial analyst with Stratus Wealth Advisors in Kensington, Md., was her income and expenses. “What are my expenses and how might they change?” was one of the first questions they needed to answer, and she’s still trying to answer it.

On the income side, she also needed to know, based on her annual spending, how her reduced income may require withdrawals from her SEP-IRA, a retirement plan for the self-employed.

Mr. Brownell (who is also her nephew) said a decision to wait until 70 was important since you’ll need to “look at your cash flow during that time. The increase in the Social Security benefits depends on the individual’s year of birth,” he said. “For example, if you were born after 1943 and you delay your benefits to age 70, your annual increase is 8 percent per year.”

Another piece of the transition is tax planning. Withdrawals from defined-contribution plans like SEP-IRAs and 401(k)s are taxable on the federal level, while pulling money out of a Roth IRA is not — if you’re at least 59½ and have kept the money in the account for at least five years.

There’s also a tax wrinkle down the road with defined-contribution plans: The Internal Revenue Service requires that most people start taking money out at age 72 in required minimum distributions. That rule, however, doesn’t apply to qualified Roth withdrawals.

Converting a conventional IRA to a Roth, which will generate a one-time tax bill from the I.R.S., might be in order, depending upon your income. Mr. Brownell recommended that workers consider this move well before retirement to save taxes down the road.

“Roth converts may be paying lower federal income tax in their ‘cutting back’ years,” he added. Because of the tax hit with a Roth conversion, you will need to talk with your tax or financial planner, or run numbers on an online calculator, to see if it makes sense for you.

D.I.Y., or Get Help?

You can, of course, manage the transition yourself or get some professional help. Finding a fee-only certified financial planner is a good start. It’s possible to find a planner who will work for a flat fee or hourly rate. Don’t hire anyone who wants to sell you investment products.

Hands down, increasing your nest egg during your in-between time is always a good idea. For 2022, you can contribute $20,500 to your 401(k) or other defined-contribution plans. That’s $1,000 more than last year. People over 50 can add $6,500 in catch-up contributions.

More important, one of your key questions should be, “What do I truly want to do and how do I get there?” Whether you are envisioning partial or full retirement, it helps to have some specific goals. For Ms. Sterner, one of those goals is having more time to engage with her local network. “I have worked nationally and internationally my entire career,” she said. “I am finding huge enjoyment volunteering in my local community.”

Ultimately, your quality of life is the biggest factor. In Ms. Sterner’s case, that involves “managing my finances, so instead of wrangling clients I can be wrangling lake trout from my kayak.”