SDP Calculator — Savings Deposit Program

The SDP calculator is a free, browser-based tool that shows what a deployed service member earns in the military Savings Deposit Program, which pays a guaranteed 10% annual return on deposits up to $10,000. Enter your deposit and deployment length to see your interest, final balance, and the gain over a normal savings account.

How the SDP Calculator Works

The Savings Deposit Program (SDP) allows deployed service members to deposit up to $10,000 and earn 10% annual interest, compounded quarterly. This calculator computes your SDP earnings over your deployment period and compares them to what you would earn in a regular savings account at a rate you specify. The difference shows you the financial advantage of maximizing your SDP contributions.

The SDP uses the compound interest formula: A = P(1 + r/n)^(nt), where P is the principal deposit, r is the annual interest rate (0.10 for SDP), n is the number of times interest compounds per year (4 for quarterly), and t is the time in years. Interest continues to accrue for 90 days after you leave the combat zone.

SDP Eligibility and Rules

To be eligible for the Savings Deposit Program, you must be a member of the uniformed services deployed to or serving in a designated combat zone for at least 30 consecutive days (or at least one day in each of three consecutive months). You must be receiving Hostile Fire Pay or Imminent Danger Pay. The maximum deposit is $10,000, and you can make deposits as a lump sum or in installments throughout your deployment.

Interest begins accruing on the date of deposit and continues for up to 90 days after you leave the combat zone. After 90 days, the interest rate drops to the standard rate set by the Department of Defense. Your principal and interest are available for withdrawal upon redeployment, though you should request withdrawal through your finance office.

Why SDP Is One of the Best Investment Returns

The SDP offers a guaranteed 10% annual return with zero risk — backed by the U.S. government. For comparison, high-yield savings accounts typically offer 4-5% APY, Treasury bonds yield around 4-5%, and the stock market averages about 10% annually but with significant risk and volatility. The SDP gives you stock-market-level returns with savings-account-level risk.

On a full $10,000 deposit over a 12-month deployment (plus 90 days), you would earn approximately $1,038 in interest. That same $10,000 in a 4.5% savings account would earn about $459 — a difference of nearly $580. The SDP advantage grows with longer deployments.

Tips for Maximizing SDP Benefits

• Deposit early: The sooner you deposit, the more interest you earn. Try to deposit the maximum $10,000 as early in your deployment as possible.
• Use the full $10,000: Even if you need to save up, getting to the max deposit is worth it. Consider using savings or a small loan that costs less than 10% to fund it.
• Remember the 90-day extension: Interest continues for 90 days after you leave the combat zone, so there is no rush to withdraw immediately.
• Track your interest: Check your SDP balance through myPay to verify interest is being credited correctly.
• Plan your withdrawal: Contact your finance office to initiate withdrawal. Funds are typically available within 30 days of your request.

Is SDP Interest Taxable?

Yes — and this is the part most SDP guides skip. Combat-zone pay is excluded from federal income tax, but the interest the Savings Deposit Program pays on it is not. DFAS treats SDP interest as ordinary taxable interest income and reports it to you and to the IRS, so it belongs on your return for the year it is credited (DFAS — Savings Deposit Program).

What that means in practice: the 10% headline rate is a pre-tax rate. A service member in the 22% federal bracket keeps roughly 7.8% of it after tax — still far above any high-yield savings account, but worth knowing before you plan around the gross figure this calculator shows. State treatment varies by your state of legal residence.

How to Enrol and Deposit Into SDP

Enrolment is not automatic. You start SDP through your deployed finance office or disbursing officer once you have served the qualifying time in the combat zone — deposits can be made by allotment from pay, cash, or check, and only unallotted current pay and allowances qualify. Balances and credited interest then appear in myPay, which is the fastest way to confirm the quarterly interest actually posted.

Two timing traps to avoid: deposits made in the final weeks of a deployment earn very little because interest compounds quarterly, and leaving money in beyond the 90-day post-deployment window drops the return to the standard DoD rate rather than 10%.

Last updated: 22 August 2026.