On the same 65.000 € gross, a worker takes home roughly 14 595 zł more per year in Poland than in Germany. That gap reflects the tax structure alone — before rent, healthcare, or savings behaviour come into play.
Housing is the first multiplier. Poland has moderate rent pressure, while Germany has moderate rent pressure. The two markets behave similarly, so most of the gross-to-net advantage flows straight into disposable income.
Healthcare and pensions go in the opposite direction. Poland runs a public healthcare model — NFZ public system with growing private supplements. Germany uses a public model — Statutory health insurance (~14.6% split with employer) gives full coverage. The country with lower take-home often shifts costs that the other country leaves to your private budget.
Net-of-everything, a relocation decision should weigh strong public welfare in Poland against comprehensive welfare state in Germany, plus differences in pension capture, social safety nets, and city-level cost of living.