Q: Bitcoin and German/US Tax law

A: The answer to this question largely depends on whether you are US tax resident. If you are a US Citizen, Green Card Holder (Permanent Resident) or reside in the US long enough during the year that you are treated as a resident for tax purposes (depending on your visa type), then you are taxed on your Bitcoin transactions whether your Bitcoins are physically located in Germany or in the US. It does not matter which bank account you use to receive the money from selling the Bitcoin or whether you gift it to your spouse (though this may present additional issues if your spouse is not also a US tax resident). Although you did not ask this, if you are a US tax resident you are taxed on any income you earn anywhere in the world, so you would be taxed on any other income you make in Germany including earnings on any bank accounts or investment accounts. You also may have reporting obligations such as FBARs, IRS Form 8938 or various other reporting forms that you need to file based on the amount of money that is in your German bank account and any other investments outside the US you may have.

The IRS has released an FAQ to help people understand the taxation of Virtual Currency/Bitcoin transactions. You can find it here: https://www.irs.gov/newsroom/irs-virtual-currency-guidance

If you are not a US tax resident, then the answer may depend largely on treaty benefits or various other issues specific to you.

Either way, I strongly suggest using an experienced tax professional to help you determine your filing obligations and perhaps to review prior year's filings if those may be incorrect as well. You will want to look for someone with experience dealing with taxation and reporting of offshore income and assets because your average tax professional (CPA, unlicensed tax preparer, etc.) typically does not have much experience with these sorts of issues.