Borrowing capacity and your budget: calculating a scenario

Start with a repeatable household budget

Enter stable household monthly net income in PLN. Treat a one-off bonus, reimbursement or irregular receipt separately: the model assumes the same payment ability throughout the chosen period. It does not convert currencies or verify income. You decide which receipts are repeatable and documented.

Enter living costs without existing debt payments or the extra reserve, which have separate fields. Include everyday spending and reasonably allocated irregular expenses. Avoid subtracting the same payment under both costs and commitments. Do not enter zero simply because you do not yet know the bank’s cost assessment.

Two limits on a new payment

The first payment room is income minus living costs, existing commitments and the reserve. The second is income times your chosen share for all payments, less existing commitments. The calculator uses the smaller value and floors it at zero. Existing commitments therefore affect both constraints.

The 40% share is an illustrative setting, not a safe level for every household or a universal bank limit. The reserve remains after costs and payments; it is not additional income. If payment room is zero, the model amount is zero, describing the assumptions rather than a formal bank rejection.

Worked example: PLN 10,000 income

Assume PLN 10,000 income, PLN 4,000 costs, PLN 1,000 existing payments, PLN 1,000 reserve and a chosen 40% share. The first surplus is PLN 4,000, but the second limit is 10,000 × 40% − 1,000 = PLN 3,000. The new model payment is PLN 3,000.00, not PLN 4,000 or 40% of income without subtracting commitments.

At 0% interest, zero buffer and 120 months, the model amount is 3,000 × 120 = PLN 360,000.00. This deliberately simple example can be checked by hand; it is not an interest-free offer. With a positive rate and the same payment, part of the payment covers interest, leaving a lower principal amount.

Compare the base rate and your chosen buffer

Enter an annual nominal rate, not APR/RRSO. The buffer adds percentage points: 6% + 2 points gives 8%, not 6.12%. These are explicit illustrative values to replace. We do not fetch offers, forecast rates or reproduce a current bank-required buffer under Recommendation S.

For positive monthly rate i and n months, principal P is payment × [1 − (1 + i)^(−n)] / i. Monthly i is the scenario’s annual rate divided by 100 and by 12. Base and stressed amounts represent two separate constant-rate scenarios, not a variable-rate schedule within one contract.

Source: UOKiK — mortgage payments, interest rates and simulation limitations.

A bank checks substantially more

KNF describes a comprehensive assessment of repayment sources, typical living costs, commitments and lending period. Banks verify records and apply their risk policies. This form does not reproduce scoring, BIK history, employment type, age or future income stability. Its result and bank approval are not outputs of identical algorithms.

Unused-card and credit-limit burdens, down payment, collateral, LTV and shortened assessment horizons are also excluded. Choosing 30 years does not establish that a bank will assess capacity over 30 years. Commissions, insurance, fees and schedule-rounding adjustments are omitted; the complete offer needs separate review.

Source: KNF — Recommendation S, June 2023, recommendations 8–9 (context, not a bank algorithm).

Use the result for comparison, not commitment

Keep the budget, rate, buffer and term alongside the model amount. Compare scenarios such as higher living costs or a larger reserve without treating the largest result as an offer. Then review a specific loan’s actual payment and complete costs. Zero means no payment room under the entered assumptions, not a verdict on credit history.

Do not provide your name, account number or banking access: the form needs only figures and calculates in the browser. Inputs are not stored persistently by default or captured in analytics. If printing a result for a lender discussion, keep the assumptions and the statement that it is your model, not a financing commitment.

Frequently asked questions

Calculators covered by this guide