The quickest way to improve your creditworthiness (bonita) is to cut the monthly commitments the bank counts. At 5.00 % over 30 years, every CZK 1,000 of monthly payments takes roughly CZK 186,000 off your maximum mortgage. Banks count not just the payments you actually make but also credit card and overdraft limits you never touch, so cancelling those before you apply is the cheapest step of all.
The second big lever is income: a co-applicant, side income you can document and, if you are self-employed (OSVČ), a tax return planned a year or two ahead. Below are 12 concrete steps with their effect in koruna, and a short list of things that do not help. All calculations use the usual internal bank threshold, which lets payments on all debts take up to 45 % of net income (50 % under 36). The ČNB itself sets no DSTI limit; it was deactivated on 1 July 2023.
How does the bank work out your creditworthiness?
Creditworthiness answers one question: what payment can you carry? The bank takes the household's net income, subtracts payments on existing loans and a notional charge for credit limits, and compares what is left with its internal threshold, usually 45 % of income (DSTI) or 50 % for applicants under 36. It also looks at total debt against annual net income (DTI), where the internal ceiling is usually 8–9.5 times, at the household's living costs and at the credit registers. Internal scoring fills in the rest.
The maximum loan follows from the maximum payment. At 5.00 % over 30 years, every CZK 1,000 of payment supports a loan of CZK 186,282; over 25 years, CZK 171,060. Every figure in this article rests on that conversion.
A ready-made table by net income is in our guide to how banks count your income.
From CZK 3.1 to 4.6 million without a pay rise
Step 1: he cancels the card and the overdraft. The payment available rises to CZK 20,250, enough for CZK 3,772,203 (+CZK 670,614).
Step 2: he pays off the car from savings (CZK 95,000). The payment available rises to CZK 24,750, enough for CZK 4,610,470 (+CZK 838,267).
For CZK 95,000 of savings and two cancelled contracts, his maximum mortgage grew by CZK 1.51 million. DTI stays comfortable: 8 times his annual income is CZK 5,280,000.
Mind the order, though. Money used to clear old loans must not leave a hole in your own funds for the purchase, where you need at least 20 % of the price (10 % under 36). If you cannot cover both, consider consolidating small loans into the mortgage.
What does each of the 12 steps add to your maximum mortgage?
Effects are calculated for Tomáš from the case above (5.00 %, 30 years, 45 % threshold) unless stated otherwise.
| # | Step | Impact on max. mortgage |
|---|---|---|
| 1 | Cancel an unused credit card (CZK 80,000 limit) | +CZK 447,076 |
| 2 | Cancel an overdraft (CZK 40,000 limit) | +CZK 223,538 |
| 3 | Pay off a small loan with a CZK 4,500 payment | +CZK 838,267 |
| 4 | Add a co-applicant with a net income of CZK 30,000 | +CZK 2,514,802 (to CZK 7,125,272) |
| 5 | Extend the term from 25 to 30 years | +CZK 376,734 |
| 6 | Negotiate 4.59 % instead of 5.00 % | +CZK 223,071 |
| 7 | Applicant or co-applicant under 36 (50 % threshold) | +CZK 512,274 |
| 8 | Document a side income of CZK 5,000 net | +CZK 419,134 |
| 9 | More own funds or a cheaper property | lower loan needed; LTV below 80 % often means a better rate too |
| 10 | 12+ months with your employer, outside the probation period | decides whether the bank recognises the income at all |
| 11 | Self-employed: tax return set up 1–2 years ahead | higher tax base = higher recognised income |
| 12 | A clean record in the credit registers | decides approval and the rate |
Step 6 also works in reverse: at the price-list 5.79 % (Hypoindex, October 2026) Tomáš can borrow CZK 387,759 less than at 5.00 %. In September 2026 the “from 4.59 %” rate is Moneta's, with a one-year fixation and conditions attached: LTV up to 80 %, an active account and insurance.
Which income the bank recognises, and how to prove it
If you are employed, the probation period (zkušební doba) is the main hurdle. Most banks do not accept income during it, and some recognise it after three months with the employer's confirmation. If you are planning a job change, apply for the mortgage first or wait until probation ends. Banks usually average regular bonuses over a longer period, so a one-off pay rise just before you apply will not help.
If you are self-employed, the bank works from your tax returns for 1–2 years, not from turnover. Someone claiming 60 % flat-rate expenses (paušální výdaje) on income of CZK 1,200,000 has a tax base of CZK 480,000, or CZK 40,000 a month, and that is the figure the bank uses.
So if a mortgage is on the horizon, consider claiming actual expenses instead of the flat rate in your last returns, or simply optimising less; the extra tax is the price of higher recognised income. The flat-rate tax regime (paušální daň) makes things harder, and many banks then recognise only a fixed share of revenue. More in our article Mortgage for the self-employed.
Side income such as rent from another property (backed by a lease and a tax return), work under agreements outside employment (dohody), parental allowance or maintenance is treated differently by each bank. All of them want it regular and visible on your account.
Check the registers before the bank does
Before you apply, request your reports from the SOLUS and BRKI/NRKI credit registers. Look for three things: forgotten loans and limits (an old department-store card counts just like your current one), records of late payments, and guarantees for other people's loans. A wrong record can be disputed with the creditor, but that takes weeks. Also check that every limit you think you cancelled really is closed. The bank needs confirmation that the contract has ended, and a zero balance is not enough.
If you have a negative record, our article on mortgages with a register record sets out what to do. If a bank has already turned you down, start with What to do if I don't get a mortgage.
What will not improve your creditworthiness
- A consumer loan for your own funds. It raises your payments, and banks check where own funds come from, so you end up with a smaller mortgage, not a bigger one.
- Repaying a loan without closing the limit. A paid-off overdraft with the facility still open still counts.
- Hiding a debt. The bank will see it in the register, and the mismatch with your application hurts your score more than the debt itself.
- A one-off higher salary. Banks work with an average over several months or with an income confirmation.
- Applying at five banks at once. Repeated register queries look bad; one pre-approved offer and a comparison of conditions works better.
- A longer term than your age allows. The term is capped by the older applicant's age, so 30 years is not open to everyone.
Recalculate your maximum after each step in the How much can I borrow calculator.
Sources
- ČNB – deactivation of DSTI (1 July 2023) and DTI (1 January 2024), LTV limit
- Act No. 257/2016 Coll., on consumer credit, § 86 (creditworthiness assessment)
- Act No. 586/1992 Coll., on income taxes, § 7 (flat-rate expenses of the self-employed)
- Swiss Life Hypoindex – advertised rates, October 2026