Steuergo, who I use to submit my yearly tax return sent me this:
If you want to receive more net from gross income in 2025, you should apply for an income tax allowance at an early stage. This directly reduces your monthly tax burden and thus ensures a higher net income. Employees with high income-related expenses, special expenses or extraordinary burdens in particular benefit from this option.
https://www.steuergo.de/blog/mehr-netto ... fuer-2025/
I think you just have to fill in some paperwork and sent it off... old school German paperwork

Anyone know if it is worth the effort? I know that will depend; as always; but consider FT employee, €50K Gross, no real deductables as a baseline