By enrolling in a flexible spending account, service members contribute funds that aren't subject to payroll taxes, which lowers their taxable income and results in more take-home pay. The money can be used for before and after school care, nanny expenses, au pairs, babysitting, day care and nursery school, and summer day camps, as well as care for adults who can't take care of themselves.

[RELATED: Pentagon Releases New Exceptional Family Member Plan]

The Defense Department estimates that roughly 400,000 service members will qualify for an account, including those with children under age 13 or who have older dependents, including spouses, with special needs who require around-the-clock care.

Those entitled to enroll include active-duty DoD service members, as well as National Guard and reserve members on Title 10 orders of at least 180 days or more, although those troops can sign up for the program with pending orders 31 days before or 60 days after activation.

Currently, Guard and reserve members on Title 32 orders, other reserve members and Coast Guard personnel are not eligible.

Service members can enroll for the new program during the federal benefits season from mid-November to mid-December -- exact dates to be announced by the Office of Personnel Management. The accounts will be active effective Jan. 1.

[RELATED: Plan Ahead With Your Family for a Smooth Transition From Active Service]

To help service members understand the benefits and limitations of DCFSAs, the DoD Office of Financial Readiness has included information on the accounts on its website. Military OneSource has launched an education campaign on the benefit with updated fact sheets, and FSAFeds, the federal office that manages the program, has a wealth of details on how to enroll and use the program.

During a press conference with reporters Thursday, DCFSA Executive Director Jennifer Walker and Andy Cohen, director of the Office of Financial Readiness at the DoD, acknowledged that the program is new and may not be well understood by service members who haven't used similar accounts.

Cohen said DoD personal financial professionals or MilTax consultants will provide a free consultation on how the benefit can affect a family's finances.

"This is a tool to help families find affordable child care, and it's vital for maintaining overall military readiness," added Walker.

[RELATED: MOAA President Outlines Key Priorities for New House Quality of Life Panel]

While the first opportunity to sign up will be during the federal benefits open season, military personnel will have additional times when they can start an account, during periods known as qualifying life events. These include a change in employment status; marriage; divorce; birth or adoption; change in child or elder care providers; change in coverage; deployment; and permanent change of station orders.

Once service members enroll, the Federal Flexible Spending Account Program will work with their payroll providers to ensure that the funds are deducted from pay. Members have a FSA savings account that they can access through an app. They then can choose to have funds paid directly to providers or submit a claim to receive the funds.

Walker said that, while there are segments of the military population who aren't eligible to access the benefit, the DoD is "continuing to work through the complexities of extending this benefit for those additional populations."

"[We] understand there are concerns from that population. We will share more information when it is available," Walker said.

[RELATED: Financial Resources From MOAA]

Cohen encouraged members to learn more about the program and reach out to a DoD financial counselor or Military OneSource to learn more.

"The counselors can help walk them through the pros and cons to determine if the DCFSA is right for them and help them make that informed financial decision," Cohen said.

Even those who don't want to enroll should consider reaching out to these resources to learn more about DoD financial programs, he said.

"They're available to help with any other financial questions that folks have about making sure that they're building financial well-being," Cohen said.