12 months before, strategic decisions
Map every contract with a notice period: insurance, broadband, mobile, gym, banking. Most German contracts auto-renew if not cancelled 3 months in advance.
Review every pension wrapper: gesetzliche Rente, bAV, Riester, Rürup, private Rentenversicherung. Decide which contracts to keep, pause or terminate. Pause is usually better than termination for fondsgebundene Rentenversicherung.
If you might be exposed to Wegzugsbesteuerung (≥1% in a corporation, 7+ years of German tax residency): involve an international tax advisor now. Last-minute planning rarely works.
Plan your exit tax year. Moving in January gives you a full year of low-income German tax treatment; moving in December does the opposite. Big effect on flat-tax KESt rates.