Kosten koper (k.k.) means all additional transfer costs are borne by the buyer. This is standard in the Netherlands for existing properties.
The largest cost is transfer tax: 2% of the purchase price. First-time buyers under 35 are exempt for properties up to €555,000 (2026).
Additionally you pay notary fees (€1,200–€2,000 for two deeds), mortgage advice (€1,500–€3,000), valuation report (€600–€900), and optionally a building inspection (€300–€500).
Example: for a €400,000 property you’ll pay approximately €12,000–€18,000 in additional costs. This money must come from your own funds — it cannot be included in the mortgage.
Transfer tax has three rates depending on who's buying and why. First-time buyers aged 18–35 purchasing their first home pay 0% up to €555,000 (2026) — an exemption you can only use once in your lifetime. Other owner-occupiers pay 2%. Investors and buyers of a second home pay 8% (reduced from 10.4% on 1 January 2026).
Kosten koper applies to existing homes. New-build properties are often sold 'vrij op naam' (v.o.n., ‘free of name’): the developer already includes transfer tax, notary fees and agent commission in the asking price. For new construction, always check whether the price is k.k. or v.o.n. — it makes a 4–6% difference in the cash you need upfront.
Why you can’t finance these costs into the mortgage: you may borrow at most 100% of market value. The purchase price is normally already equal to or above that value, so there is no headroom above the mortgage into which the additional costs could be folded. Overbidding widens the gap: bid €30,000 over asking on a home that values at the asking price, and that €30,000 lands on top of your own cash requirement.
The first-time buyer exemption carries conditions beyond age. You must be 18–35 at the moment of transfer at the notary (not when you sign the purchase agreement), you must occupy the home as your main residence, and you must never have used the exemption before — including in a previous relationship. If you buy together and only one of you qualifies, the exemption applies only to that person’s share of the property.
A few line items are optional but rarely wise to cut. A building inspection (€300–€500) is the cheapest way to find deferred maintenance, foundation problems or wood rot before you commit — on a €400,000 purchase that is well under a tenth of a percent. A buying agent (€2,000–€4,000) is a bigger item; weigh it against how many bidding rounds you expect and how well you already know the neighbourhood.
Budget for costs after transfer that sit outside the k.k. percentage too: moving, any movable goods taken over from the seller, immediately necessary repairs, and the first bills for property tax, water authority and sewerage charges. Many buyers put their last euro into the bid and get squeezed afterwards. Deliberately keep a buffer alongside your kosten koper.
Shop around on the individual items. Notary fees genuinely differ by hundreds of euros for identical work, and as the buyer you are free to choose your own notary — even when the selling agent proposes one. The same goes for mortgage advice: the €1,500–€3,000 range is real and depends on the adviser, not on how complex your application is.