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Merging two flats into one in Poland: mortgage, bank consent and formalities

How to buy the neighbouring flat with a mortgage in Poland and merge it with yours: the bank’s consent, the owners’ resolution, a building permit for a load-bearing wall, the certificate of a self-contained unit and one land register.

Piotr Sułkowski · mortgage expert, KNF RHA0013513
Updated:

In short

You can buy the flat next door with an ordinary Polish mortgage, but turning two flats into one is a separate procedure: a resolution of the owners’ association, a building permit if you touch a load-bearing wall, a certificate that the new flat is a self-contained unit, and a notarial deed after which there is one land register (księga wieczysta). If a flat has a mortgage, the bank must agree, because its security changes. In our example one loan secured on both flats lets you buy the neighbour’s flat for 400,000 zł and renovate without the 140,000 zł in cash that a separate loan would need.

How to finance the flat next door

  1. A separate mortgage on the second flat. The bank secures the loan only on the flat you buy. You need a down payment, usually 20% of the price, and the renovation is paid from savings. Simple at purchase, but harder when merging, because two loans, often in two banks, then concern one flat.
  2. A mortgage on both flats. If your flat is paid off or nearly paid off, the bank can also take a mortgage on it, and the value you already own can replace the down payment.
  3. One loan for everything. A new bank repays your current loan, finances the purchase and the renovation and takes a mortgage on both flats. After the merger there is one loan, one mortgage and one flat.

Example: the flat next door for 400,000 zł

Your flat is worth 520,000 zł with 230,000 zł left to repay. The neighbour sells for 400,000 zł, and merging and renovation cost 60,000 zł.

Separate loanOne loan on both
New loan320,000 zł690,000 zł
Cash for down payment and works140,000 zł0 zł
Loan-to-value80%75%
Instalment of the new loan2,023 zł + current4,361 zł
30 years at 6.5%, equal instalments. Details

Transaction costs come on top, including the 2% tax on civil law transactions (PCC), here 8,000 zł. Banks calculate differently.

A Polish mortgage agreement usually requires the bank’s consent to changes in the property that secures the loan. Merging is such a change: two land registers are closed and a new flat with a different area and value is created. The mortgage does not disappear. If each flat has a loan in a different bank, one loan usually has to be repaid or moved to the other bank before the merger.

Formalities step by step

  1. Owners’ resolution. Merging two flats that are separate properties requires the consent of the owners expressed in a resolution (art. 22(4) of the Act on the ownership of premises). If they refuse, you can ask a court to decide. In a small association of up to seven flats all co-owners must agree.
  2. Building permit for structural works. In a block of flats, works that do not touch external walls or structural elements need neither a permit nor a notification. An opening in a load-bearing wall or a ceiling needs a building permit (art. 29 of the Construction Law).
  3. Certificate of a self-contained unit. After the works the district office (starosta) or the city issues a certificate that the new flat is self-contained. The stamp duty is 17 zł.
  4. Notary and one land register. The notary prepares the deed, and the court closes the two land registers and opens one for the new flat, with the bank’s mortgage entered there.

Do not knock through the wall before you have the consents: works on a load-bearing wall without a permit are an unauthorised construction, and the bank may treat it as a breach of the loan agreement. A longer version of this article is available in Polish, and the general rules for foreigners are in our guide mortgage for foreigners.

Frequently asked questions

Can I buy the neighbouring flat with a mortgage in Poland?

Yes. It is an ordinary purchase mortgage. If your current flat is paid off or nearly paid off, the bank may take a mortgage on both flats, which reduces the down payment you need.

Do I need the owners’ association to agree to merge two flats?

Yes. Merging two flats that are separate properties requires a resolution of the owners. If they refuse, you can ask a court to decide.

Do I need a building permit to merge two flats?

Only if you make an opening in a load-bearing wall or a ceiling in a block of flats. Works without structural elements need neither a permit nor a notification.

Sources

  1. Act on the ownership of premises, art. 2 and 22 (ISAP, Polish)
  2. Construction Law, art. 29 (ISAP, Polish)
  3. Act on land registers and mortgages, art. 21 (ISAP, Polish)
  4. Polish Financial Supervision Authority (KNF): Recommendation S on mortgage lending
This guide describes general rules and typical bank practice as of October 2026. Details

It is not legal or tax advice and not a bank offer. Each bank sets its own criteria, and the lending decision is always made by the bank.

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