You owe US taxes on worldwide income so that income is also taxed by the IRS. However, you get a dollar-for-dollar credit on taxes paid to Germany so you're probably safe from double-taxation. Read up on the Foreign Tax Credit and Form 1116. Turbotax and its competitors probably handle this. Here's turbotax's blurb on it: https://turbotax.intuit.com/tax-tips/military/filing-irs-form-1116-to-claim-the-foreign-tax-credit/L2ODfqp89