A buy-to-let mortgage in the Czech Republic is a loan for a flat bought to let, or for your third and further property. Since 1 April 2026 the ČNB (Czech National Bank) recommends that banks cap such loans at LTV 70 % and DTI 7; it is a recommendation, not law, but banks follow it. On a CZK 5 million flat you need at least CZK 1.5 million of your own money.
DTI 7 catches out more people than the deposit. Your debts must stay within seven times your net annual income, and DTI adds up all of them, the mortgage on the flat you live in included. A family still paying off CZK 3,000,000 on its own flat that wants to borrow CZK 3,500,000 for an investment flat needs net income of at least CZK 77,381 a month.
For your own home the only binding limit is still LTV 80 % (90 % if at least one applicant is under 36).
When does a mortgage count as buy-to-let?
The ČNB treats a mortgage as an investment mortgage in two cases: you are buying a third or further residential property, or you are buying a property to let, even if it is only your second. The recommendation covers loans granted from 1 April 2026 and leaves older mortgages alone.
How properties are counted is spelt out in each bank's rules. Komerční banka, for example, includes cooperative flats and property abroad, and treats as yours any property of which you own at least 50 %. It also counts as residential a holiday home that can be lived in all year round and is connected to the utilities.
The purpose can't be hidden. If you want the bank to include future rent in your creditworthiness, it will treat the mortgage as an investment one. And if you declare that you will live in the flat and then let it out, you are in breach of contract. The consequences are covered in Mortgages and Airbnb lettings.
DTI 7 counts every debt you have
The income you need depends not on the price of the investment flat but on the sum of all your debts once you have bought it. Below is the minimum net household income at DTI 7 and, for comparison, at DTI 9, which banks usually apply internally to owner-occupied homes.
| Total debts after the purchase | Net annual income at DTI 7 | Monthly at DTI 7 | Monthly at DTI 9 |
|---|---|---|---|
| CZK 3,000,000 | CZK 428,571 | CZK 35,714 | CZK 27,778 |
| CZK 4,000,000 | CZK 571,429 | CZK 47,619 | CZK 37,037 |
| CZK 5,000,000 | CZK 714,286 | CZK 59,524 | CZK 46,296 |
| CZK 6,500,000 | CZK 928,571 | CZK 77,381 | CZK 60,185 |
| CZK 8,000,000 | CZK 1,142,857 | CZK 95,238 | CZK 74,074 |
DTI is not the only brake, though. The bank still checks what share of your income goes on repayments (DSTI) against its internal threshold, usually 45 % of net income. With rates around 5 %, DSTI often turns out to be the stricter of the two, as the example below shows. How the two ratios differ is explained in DSTI, DTI and LTV explained.
The Horáks buy a second flat to let
A model case: a two-room flat (2+kk) for CZK 5,000,000 (assume an older flat outside central Prague, rent of CZK 20,000 a month, one month a year empty, and running costs for the repair fund, insurance and property tax of CZK 20,000 a year; an investment mortgage of CZK 3,500,000 over 30 years at 5.00 %; the Horáks are also paying off CZK 3,000,000 on their own flat with a repayment of CZK 17,538 over 25 years at 5.00 %):
- Own funds: CZK 1,500,000 (LTV 70 %), plus the valuation and lien registration.
- Investment mortgage repayment: CZK 18,789 a month, CZK 225,465 a year.
- DTI 7: total debts of CZK 6,500,000, so they need net income of at least CZK 928,571 a year, or CZK 77,381 a month.
- DSTI 45 %: repayments total CZK 36,327, so without counting the rent they need net income of at least CZK 80,725 a month.
- Cash flow: 11 months' rent of CZK 220,000 minus CZK 20,000 of costs leaves CZK 200,000, which is 4.0 % of the price. After the mortgage repayment that is −CZK 25,465 a year, roughly −CZK 2,122 a month.
Negative cash flow is not the same as a loss. CZK 51,638 of the first year's repayments goes towards the principal, so the Horáks' wealth grows even if the flat's price stands still. But a net yield of 4.0 % is below the interest rate, so every borrowed crown lowers the return on their own money. At 6.00 % the repayment on the same loan would be CZK 20,984 and cash flow would drop to roughly −CZK 4,318 a month.
Run your own figures in the investment property calculator. The gross yield on this flat is 4.8 %; how that differs from the net yield, and why it matters, is explained in the glossary.
Will the bank count future rent as income?
Only some banks, and only in part. Banks count rent cautiously, and each in its own way. For a letting that is already running they usually want a tax return showing income under § 9 and the tenancy agreement. Even then they recognise only part of it, because they allow for empty months and repairs. Rent from a flat you are only now buying is counted by just some banks, typically on the strength of a signed tenancy agreement or an estimate of market rent, and with a deduction.
So plan for your other income to carry both repayments. When a tenant moves out, the bank still wants its money.
If you are short of own funds, you can pledge another property in place of part of the cash, such as your own unmortgaged flat or your parents' house. How this additional collateral works, and what the person providing it risks, is described in Using parents' property as mortgage collateral.
Interest on a let flat goes into expenses
Income from long-term letting is taxed under § 9 of the Income Tax Act. The interest deduction under § 15 (up to CZK 150,000 a year) does not apply to a let flat. You can still claim the interest as an expense if you opt for actual expenses. The alternative is flat-rate expenses of 30 % of income (capped at CZK 600,000), and with those you can't claim interest or any other costs separately.
The Horáks pay CZK 173,827 in interest in the first year. With actual expenses their tax base comes to 220,000 − 173,827 − 20,000 = CZK 26,173, and that is before any depreciation of the flat. With flat-rate expenses the base would be CZK 154,000. At a 15 % tax rate, that means CZK 3,926 against CZK 23,100 a year.
Depreciation of the flat lowers the base further. How it is calculated, and when the flat rate works out better, is explained in our guide to rental income tax.
Interest falls as you repay, so the advantage of actual expenses shrinks over time. When you sell, the gain is tax-free if you have owned the flat for at least 10 years; the exemption after 2 years of living in a property does not apply to a flat you never lived in. The wider picture is in our article Mortgages and taxes.
Before you sign a reservation
- You have 30 % of the price, plus the cost of the valuation, lien registration and any agent's commission, or a property you can offer as additional collateral.
- All your debts after the new mortgage come to no more than seven times your household's net annual income.
- You can carry both repayments without the rent, at least for as long as the flat stands empty.
- Your cash flow still works at a rate 1 pp higher, because you will be renegotiating the rate when the fixed period ends.
- You know whether you are buying in your own name or through a limited company (s.r.o.). A loan to a company is a business loan, and the bank judges it on the company's finances.
- Your costs include the repair fund, insurance and the annual property tax, which doubled from 2024.
Sources
- ČNB – recommendation of LTV 70 % and DTI 7 for investment mortgages from 1 April 2026
- Komerční banka – New ČNB rules for investment mortgages (how properties are counted)
- Act No. 586/1992 Coll., on income taxes, § 4 (exemption of income from a sale), § 9 (rental income, 30 % flat-rate expenses), § 15 (interest deduction)