Grunderwerbsteuer is set by your Bundesland
Each Land sets its own rate under section 11 GrEStG, from 3.5% in Bayern to 6.5% in Brandenburg, Nordrhein-Westfalen, Saarland and Schleswig-Holstein. Nothing else about the purchase changes: same house, same loan, same monthly payment. Only the bill on completion day moves, and it moves by tens of thousands.
Worked example: the same house, two German states
A 400,000 euro home in Bayern pays Grunderwerbsteuer at 3.5%, so 14,000 euros. The same house in Nordrhein-Westfalen pays 6.5%, so 26,000.
Add notary, land registry and the buyer's share of the agent fee, about 3.5% or 14,000 euros, and completing costs 28,000 in Bayern against 40,000 in NRW. The monthly payment is identical. The cash you need is 12,000 euros apart.
Leave the Bundesland unset and the calculator falls back to a 5% national placeholder, which is nobody's actual rate. Rates move when a Land legislates: Bremen last changed on 1 July 2025.
No mortgage insurance, and a Grundsteuer nobody can predict
German lending has no mortgage insurance. Lenders expect the buyer to find the purchase costs in cash on top of the deposit and price whatever risk remains into the interest rate, so a small deposit shows up as a dearer rate rather than as a separate premium line.
Grundsteuer is not a percentage of what you paid. It is a formula on an assessed value multiplied by a municipal Hebesatz, reformed with effect from 2025, and the reform moved bills in both directions. About 0.15% of market value is a common outcome and the figure here, but your Gemeinde sets the multiplier and only their assessment is binding.
The agent commission has been split between buyer and seller since a law of 23 December 2020, which is why the buyer's share inside the 3.5% here is about a point and a half rather than the whole commission, up to 7.14% of the price in Berlin before the reform.