Short Answer
Your employer has the legal right to demand a medical certificate from a doctor starting from the very first day of your illness.
While the statutory default is the fourth day, individual work contracts often override this to require proof immediately.
What Most Expats Don't Realize
You stayed home on a Friday and Monday, assuming you only needed a note for a three-day stretch. You didn't know that weekends count toward the total duration of your illness, so your employer demanded a certificate that covered all four days. You lost two days of pay because you couldn't get a backdated note from a doctor on Tuesday, as German physicians will almost never backdate, and going beyond three days prior is legally impossible.
What To Do
- Read your employment contract to find the specific clause regarding "Krankmeldung."
- Book a doctor's appointment on the first morning you feel ill, even if you think you will recover quickly.
- "Ich brauche eine Krankschreibung ab heute." (I need a sick note starting from today.) — tell the doctor this to ensure your absence is legally covered.
The Truth
Germany’s medical documentation rules are inflexible. If you miss the window to see a doctor on your first day of absence, the system provides no way to legally "fix" the gap in your records later.