DSTI, DTI and LTV — all ČNB mortgage limits explained
The Czech National Bank sets three limits for mortgages that banks must follow by law. If you fail even one, the bank will deny your mortgage. Here is each one explained with concrete numbers.
LTV — Loan to Value (loan-to-property ratio)
LTV is the percentage of the property value the bank lends you. ČNB sets the ceiling at 80 % for standard applicants, 90 % for under-36s.
Example: A flat costs 6,000,000 CZK. With LTV 80 %, the bank lends a maximum of 4,800,000 CZK and you must put down 1,200,000 CZK from your own funds. With LTV 90 % (under-36s), the bank lends up to 5,400,000 CZK and you put down 600,000 CZK.
Lower LTV (less than 80 %) often means a slightly better rate — banks reward smaller risk.
DSTI — Debt Service to Income (payment-to-income ratio)
DSTI is the share of your net monthly income that goes toward all loan payments (mortgage + other loans). ČNB sets the limit at 45 %, for under-36s 50 %.
Example: Your net monthly income is 60,000 CZK. The maximum total monthly payment for all your loans is 27,000 CZK (45 % × 60,000). If you already have a 4,000 CZK car loan payment, only 23,000 CZK is available for the mortgage payment.
This is the limit that most often stops applicants — especially with high property prices and high rates.
DTI — Debt to Income (total debt vs. annual income)
DTI is total debt (mortgage principal + other loans) compared to annual net income. ČNB sets the limit at 8.5× annual income, for under-36s 9.5×.
Example: Annual net income 720,000 CZK (60,000 × 12). Maximum total debt: 720,000 × 8.5 = 6,120,000 CZK. If you already have a 200,000 CZK loan, you can borrow at most 5,920,000 CZK on the mortgage.
Which limit usually stops you
In Prague and Brno (high prices) it is most often DSTI — payments are too high relative to income. In smaller towns where prices are lower, it is sometimes LTV — you don't have enough own funds.
DTI is the limit that least often blocks applicants — it kicks in mainly for very large mortgages (8 million+) on relatively low income.
Are there exceptions?
ČNB allows banks to use a 5 % exception per quarter for clients exceeding the limits. This is rare and reserved for very strong clients (high income, large reserve, perfect credit history). Don't count on it.
The most common workaround: co-applicant (spouse, partner, parent) — combined income raises the limits.
FAQ
What if I don't meet one of the ČNB limits?
The bank will refuse your mortgage. Your options: increase down payment (lowers LTV), reduce the loan amount, extend the term (lowers DSTI), or add a co-applicant. Some banks have minimal flexibility through the 5 % exception, but don't bet on it.
Are limits the same at all banks?
ČNB sets the maximum — banks may set stricter limits internally. For example, a bank may demand DSTI 40 % even though ČNB allows 45 %. Always check with the specific bank.
How do I count income — gross or net?
Always net (after tax) for DSTI and DTI. The bank uses your statutory net income, including some bonuses if they're regular.