I have extensively covered the tax situation for US citizens in Germany on various threads. As you live and work in Germany you of course have to file and pay German taxes. Normally one has to have various clients to be self-employed but maybe there is an exception as a teacher working for the VHS? You should be likely taxed as self-employed in Germany – and cannot expect this to be seen different from the American tax authorities.
You need to file American tax returns but by taking either the Foreigner Earned Income Exclusion or Foreign Tax Credits should eliminate any federal income tax obligation. What is left is Social Security which will be applied by the IRS as a self-employer person. If you are an employee in Germany, then a German company is not withholding and paying half of your American SS contributions so EVERY American overseas in effect is seen as self-employed.
But, if you are paying your required social contributions for health, disability and retirement in Germany then you should be exempted under the German/American totalization treaty on SS benefits. You need to get an annual statement (Form D/USA-101A) that you are covered under the German system from the Bundesversicherungsanstalt für Angestellte (BFA) in Berlin. I send my request yearly by fax and they send the certified form by the post. This must be included with your IRS returns and proves you are exempt from paying any SS taxes to the States. I am including their address, web-address and fax number below.
The website shows a free 800 number for information but one usually has to get connected through to the right department in the Berlin office to get any reliable information. If you want, I can message you with the text of the form request I send. Important is to include your full name, address and German social security number
BFA Abteilung USA
BKZ 5565
Ruhrstr. 2
10704 Berlin
Fax 030 865 63848
https://www.deutsche-rentenversicherung … _node.html
One should know that Americans abroad get an automatic 2-month filing extension for federal income tax returns. One need just attach a statement to the forms informing the IRS of this situation and one's choice to make use of it. Longer extensions are possible (4 months I think) but should be applied for before April 15th.
If one has more than 10,000 USD worth of financial assets, one also usually has to file an annual FBAR form, now done online and always separate from the normal tax return as it is independent of income.
One should also know that most forms and information from the IRS are available at IRS.gov
Make sure you don land at IRS(dot)com as it is a commercial site that tries to trick people into believing they are the IRS but aren't.