You can buy a flat with a parent, a sibling or a friend, and the bank will assess it much as it would a couple. Whoever signs the loan agreement is liable for the whole debt, and every co-owner has to sign the pledge agreement. The difference from married couples is that the law settles nothing else for you: not the shares, the payments, a sale, or one of you leaving.
The decision that costs or saves the most money is who becomes a co-borrower. A parent adds income, but their age shortens the term. On a CZK 4,000,000 mortgage at 5.00 %, the gap between a 30-year and a 20-year term is almost CZK 5,000 on the monthly payment. Unmarried couples have an article of their own: Joint mortgage for unmarried partners.
Does a co-owner have to be a co-borrower?
No. A co-owner who is not a co-borrower signs only the pledge agreement, and the bank does not count their income.
| Role | What they sign | Is their income counted | What they are liable for |
|---|---|---|---|
| Co-borrower and co-owner | the loan agreement and the pledge agreement | yes | the whole debt, with everything they own |
| Co-owner only (pledgor) | only the pledge agreement | no | with the flat, not with other assets |
| Co-borrower only, with no share | only the loan agreement | yes | the whole debt, though the flat is not theirs |
Everyone signs the pledge agreement because jointly owned property can only be encumbered with the consent of all co-owners (§ 1132 of the Civil Code). A standard mortgage therefore rests on the whole flat, not on one co-owner's share.
The bottom row is the worst deal for the person signing: they pay but own nothing. If a parent joins the loan only to add income, give them at least a small share or a written right to get back what they pay.
A parent as co-borrower shortens the term
Banks want the loan repaid by the time the oldest borrower reaches a certain age, for example 70 at mBank. A 55-year-old parent therefore caps the term at 15 years, and the payment jumps. It often works better for the parent to contribute own funds and come in only as a co-owner.
Daughter and father, two set-ups (assumptions: flat for CZK 5,000,000, the father contributes CZK 1,000,000 of own funds, mortgage of CZK 4,000,000 at 5.00 %, annuity payment; the daughter is 32, the father 55, and the bank wants the loan repaid by the time the oldest borrower turns 70).
- Father as co-borrower: a term of at most 15 years, payment CZK 31,632. At the banks' usual internal threshold of 45 %, together they need a net income of about CZK 70,300.
- Father only as co-owner with a 20 % share and as pledgor: a 30-year term based on the daughter's age, payment CZK 21,473, income needed about CZK 47,700. On a net income of CZK 50,000 the daughter manages it alone.
- In both cases the LTV is 80 %, so the ČNB limit is met. The daughter is under 36, so the bank could even go to 90 %.
Here the father's million works as own funds. His share in the land registry means he will not lose the money, and the daughter keeps the long term.
Another route is using the parents' property as additional collateral instead of cash; see Securing a mortgage with the parents' property.
Can a share in a property be pledged?
Under the law, yes. Each co-owner is the full owner of their share and may deal with it without the others' consent (§ 1121 and 1123 of the Civil Code), so they may also pledge it (§ 1310). Whether a bank will take a share alone as collateral is up to the bank, and a standard mortgage rests on a lien over the whole flat, which needs the consent of all co-owners (§ 1132).
Beyond that, the law arranges little for you. Married couples have community property to sort out ownership; co-owners get only the general rules. Ordinary management of the flat is decided by a majority counted by the size of shares (§ 1126 and 1128), significant changes by a two-thirds majority (§ 1129). Encumbering the flat, which includes a new mortgage or a top-up of the existing one, needs everyone's consent.
Co-owners have a statutory right of first refusal only where the co-ownership arose in a way such as inheritance, and only for six months (§ 1124). If you bought a flat with a sibling or a friend, you have no right of first refusal at all, and the other person can sell their share to a stranger. Agree one in writing.
Nobody has to stay in co-ownership (§ 1140). Any co-owner can ask a court to dissolve it, and the court either awards the flat to one of them against compensation or orders a sale (§ 1143). The mortgage carries on in the meantime, and the co-borrowers remain liable for the full amount.
What to put in writing when you buy
- Shares and contributions: who put in how much of the own funds, and whether that is paid back first on a sale.
- Payments: who covers which part of the instalment and what happens if someone stops, for instance that their claim on the sale proceeds is reduced by the unpaid instalments.
- Use: who lives in the flat and whether they pay the others rent.
- Costs: the repair fund, insurance, property tax, repairs.
- Exit: how the flat will be valued (by an independent expert), the deadline for paying out the leaver, and the duty of whoever stays to take over or refinance the loan.
- A right of first refusal for the other co-owners.
- Death of a co-owner: the share passes to their heirs, not to the other co-owners. Think about a will and life insurance.
An agreement on managing the property made as a public deed is filed in the land registry's collection of documents (§ 1138) and also binds anyone who later buys a share. If you are buying with a friend to let the flat out, bear in mind that since 1 April 2026 the ČNB has recommended an LTV of no more than 70 % and a DTI of 7 for investment mortgages.
How a co-owned flat is taxed
- Property tax is owed by the co-owners jointly and severally (§ 13 of Act No. 338/1992 Coll.). One of them files the return for everyone, or each files for their own share (§ 13a).
- Interest can be deducted only by a party to the loan agreement who co-owns the flat and lives there, or whose spouse, children, parents or grandparents do. Either one of them claims the interest, or each claims an equal part (§ 15(4) of the Income Tax Act). The father in the co-borrower set-up above could therefore claim the deduction; a sibling who does not live in the flat could not. Details are in Mortgage interest deduction.
- If the flat is let, the co-owners must split income and expenses according to their shares. Otherwise they can claim only actual expenses, not the 30 % flat-rate allowance (§ 12(2)).
- On a sale, each seller's exemption is assessed separately. If they sell, the daughter, who has lived in the flat for two years, has her part of the proceeds exempt; the father, who does not live there, only after 10 years of ownership or if he puts the money into his own housing (§ 4(1)).
Sources
- Act No. 89/2012 Coll., Civil Code, § 1124 (right of first refusal), § 1126–1132 (management and encumbrance of jointly owned property), § 1138, § 1140–1143 (dissolution of co-ownership)
- Act No. 586/1992 Coll., on income taxes, § 4(1), § 12(2), § 15(4)
- Act No. 338/1992 Coll., on immovable property tax, § 13 and 13a (co-owners)
- ČNB – LTV limit of 80 % / 90 %, recommendation for investment loans from 1 April 2026