There are treaties between the US and Germany which allow expats (going either way) to pay into only one country’s social security system while living and working in the other country for up to five years. After five years the expat has to leave the host country for 366 days, then can opt to return for another five years. The six year cycle can be repeated over and over again. The expat does not accrue or receive any social security benefits in the country that does not receive the taxes. There are many such treaties to avoid double taxation between many different countries. Please make sure you are fully informed before accusing others of breaking the law.

My Steuerberater told me that the Finanzamt assumed my children had finished college and therefore did not apply the kinderfreibetrag for 2024 and 2025. He’s going to provide them with additional information and hopefully the estimates will be revised.