Ten thousand dollars in the Savings Deposit Program earns $1,000 a year. Guaranteed, federally backed, at 10% annual interest. No high-yield savings account in 2026 pays close to that, and no stock fund offers 10% without the risk of losing money in a bad year. The SDP just hands it to you.

The catch is that you have to be deployed to a combat zone to use it, you have to enroll while you’re there, and the interest has a deadline. Most service members either start too late and leave money on the table, or never hear about it until they’re already home and the window has closed.

Here’s how the SDP actually works: who qualifies, how to enroll, when the interest stops, and the tax detail almost every online guide gets wrong.

What the SDP is, and why 10% is extraordinary

The Savings Deposit Program is a government savings account that pays 10% annual interest, available only to troops serving in a combat zone or designated hazardous-duty area. The authority is 10 U.S.C. § 1035, and the rules live in the DoD Financial Management Regulation, Volume 7A, Chapter 51.

Put the rate in perspective. A good high-yield savings account pays maybe 4-5% right now. The stock market averages around 10% over decades, but it can drop 20% in a year, and deployment is not the time to gamble money you might need. The SDP pays 10% with zero risk to your principal because the federal government guarantees it. That makes it the best risk-free return available to any American. The only entry requirement is being deployed.

Your money compounds quarterly until your balance reaches $10,000. After that, the account pays simple interest on the $10,000 cap.

One honest thing to get straight before anything else: the interest is taxable. A lot of posts claim otherwise. They’re wrong, and I’ll show you exactly why below.

Who qualifies — exactly

You’re eligible when both of these are true:

  1. You’re serving outside the United States, its possessions, and Puerto Rico for at least 30 consecutive days, or at least one day in each of three consecutive months, and
  2. You’re either in a designated Combat Zone, or you’re drawing hostile fire or imminent danger pay in a Qualified Hazardous Duty Area or a designated direct-support area of a combat zone.

That second clause in the first rule is the part most articles skip. You don’t always need 30 unbroken days in the zone. If your deployment has you cycling in and out, qualifying for one day in each of three straight months counts too. Check the calendar before you assume you don’t qualify.

How much you can deposit

The cap that earns 10% is $10,000. You can deposit in any amount of $5 or more, and that $10,000 ceiling counts your principal plus accrued interest together. Once interest pushes your balance to $10,000, anything above it earns simple interest rather than compounding.

The play is simple: get to $10,000 as early in the deployment as you can. Every month your balance sits below the cap is 10% you’re not earning. If you’ve got cash parked in a regular account at 4%, moving it into the SDP during deployment more than doubles its rate for as long as you’re eligible.

How to enroll

You enroll in theater, through your finance or disbursing office. You can’t set it up from home before you leave, and you can’t start it after you get back.

  • Deposit unallotted pay or allowances, in amounts of $5 or more, with any disbursing officer, finance officer, or other designated officer.
  • Active-duty members can also fund it through an allotment, which is the cleanest way to do it automatically.
  • You can begin once you’ve met the 30-day (or one-day-in-three-months) threshold.

Practical version: find your finance office early in the deployment, ask to start an SDP allotment, and front-load it toward the cap.

How interest accrues, and when it stops

This is where the free money has a clock on it. Your deposits earn 10% the whole time you’re eligible. After you leave the qualifying area, interest keeps accruing for up to 90 more days, then it stops for good.

So the 10% doesn’t vanish the moment you fly home. You get a 90-day tail. But that tail ends, and any money left in the account after that just sits there earning nothing. (One precision point from the regulation: if the 90-day mark falls mid-month, interest is paid only through the end of the previous month.)

SDP, TSP, and the CZTE: what stacks and what doesn’t

Deployment opens three separate money moves, and people constantly blur them together. They are not the same thing:

  • SDP pays 10% guaranteed on up to $10,000. The interest is taxable.
  • TSP is your retirement account. While you’re deployed in a combat zone, your contributions can go in tax-free under the Combat Zone Tax Exclusion, and you can contribute well above the normal annual limit.
  • The CZTE (Combat Zone Tax Exclusion) makes the military pay you earn in the combat zone tax-free.

Now the myth worth killing: the CZTE does not make your SDP interest tax-free. Your combat-zone pay is excluded from taxes, yes. But SDP interest is investment income, and it’s taxable regardless of where you earned it. If a post tells you the SDP is “tax-free because you’re deployed,” it’s confusing two different programs.

The smart stack is to use the tax-free window to load pay into your TSP for retirement, and use the SDP to park up to $10,000 in cash at 10%. Two different jobs, both worth doing on the same deployment.

How to withdraw after you return

You request your money back after you leave the SDP area. If you never request it, the funds don’t disappear: 120 days after your departure, DFAS automatically transfers the balance to your military pay account.

Notice the gap. Interest stops at 90 days, but the automatic refund doesn’t happen until 120. That leaves a 30-day stretch where your money is sitting in the SDP earning nothing. The right move is to request your withdrawal as soon as the 90-day interest tail ends, rather than waiting on the auto-transfer. Emergency withdrawals before then are allowed if your commanding officer authorizes it.

Common mistakes

  • Enrolling late. Every month you wait is a month of lost 10%. Fund it to the cap early.
  • Never enrolling at all. The most expensive mistake, and the most common. People find out about the SDP after they’re home, when the window is already shut.
  • Assuming the interest is tax-free. It isn’t. Set aside a little to cover the tax on it.
  • Leaving money in past the 90-day tail. Once interest stops, request your withdrawal. Don’t wait for the 120-day auto-refund to do it for you.
  • Confusing the SDP with the TSP. The SDP is a short-term cash account at 10%; the TSP is long-term retirement. Do both if you can swing it.

The bottom line

The SDP is one of the few benefits with no real downside and a hard deadline. Ten percent guaranteed on $10,000 is roughly $1,000 a year you simply cannot get anywhere else, but only while you’re deployed and only if you enroll in theater. Find your finance office early, fund it to the cap fast, remember the interest is taxable, and pull your money out once the 90-day tail runs out.

Verified against the DoD Financial Management Regulation, Volume 7A, Chapter 51 (May 2025) and 10 U.S.C. § 1035 as of June 2026. Program terms can change; confirm specifics with your finance office before relying on them. General information, not financial advice.