How much can I borrow? The bank's rules and what you need to contribute yourself
ikzoek editorial team · 4 min read · 4 October 2026
Before you go house hunting, there's one thing you want to know: what's my budget? That depends on what you can borrow, what you contribute yourself and what you can spare each month without living too tightly. Banks apply rules of thumb for this, which the National Bank of Belgium (NBB) has monitored since 2020. We've listed them below and worked through a few example situations.
Rule 1: your monthly repayment stays below a third of your income
The best known rule: the total of all your credit repayments may not exceed roughly a third of your net household income. If you earn 4,200 euros net per month together, 1,400 euros is the ceiling for your mortgage plus any car loan. Banks also look at what's left after that repayment: for a family with children, they generally want to see at least 1,500 to 2,000 euros of disposable income remaining. A higher income therefore leaves relatively more room than a low one.
Rule 2: the bank lends a maximum of 90% of the value
The NBB expects banks to finance no more than 90% of the purchase value (the so-called loan-to-value ratio, or "quotiteit") for a first home. A limited portion of loans may exceed this, up to 100% for young buyers, but that's the exception and comes with a higher interest rate. For a second home or an investment property, the limit is 80%.
Pay attention to the word value: the bank has the property valued. If you bid above the valuation, it will finance 90% of the valuation, not of your bid. The difference comes on top of your own deposit.
Rule 3: you pay the costs yourself
Registration duties, notary fees, deed costs and the costs of establishing the mortgage are not financed by the bank. In Flanders, budget for around 5% of the price for a sole owner-occupied home, more in Brussels. See our overview of the registration duties per region.
What does that mean in practice?
| Property worth 280,000 euros | Property worth 380,000 euros | |
|---|---|---|
| Loan (90%) | 252,000 euros | 342,000 euros |
| Own deposit (10%) | 28,000 euros | 38,000 euros |
| Costs (approximately 5%, Flanders) | 14,000 euros | 19,000 euros |
| You need yourself | 42,000 euros | 57,000 euros |
| Monthly repayment, 25 years, 3.4% fixed | approximately 1,245 euros | approximately 1,690 euros |
| Minimum net household income (33%) | approximately 3,750 euros | approximately 5,100 euros |
These interest rates are indicative for early 2026; a quarter of a percentage point difference on 300,000 euros over 25 years makes a difference of around 40 euros per month.
The term: 20, 25 or 30 years?
A longer term lowers your monthly repayment but significantly increases the total interest cost. On 300,000 euros at 3.4%, you pay around 113,000 euros in interest over 20 years, 146,000 euros over 25 years and 180,000 euros over 30 years. Banks rarely grant more than 25 years and require the loan to be repaid before you turn 70. Choose the shortest term you can comfortably manage, and check whether your outstanding balance insurance decreases along with it.
Fixed or variable?
In Belgium, the large majority choose a fixed interest rate: certainty over the entire term. Variable formulas (for example 5/5/5 or 10/5/5) start lower but can rise, legally capped at a maximum of double the starting rate. A variable rate can be worthwhile if you expect to repay the loan early or if the interest rate curve is steep. For every quote, ask for the annual percentage rate of charge (APR), which also includes the compulsory insurance and file costs.
What improves your file?
- A larger deposit. Every percentage point below the 90% loan-to-value ratio earns you a lower interest rate.
- Stable income. A permanent contract carries more weight than a temporary one; self-employed applicants need to provide three years of figures.
- No outstanding loans. A car loan of 400 euros a month eats up a quarter of your borrowing capacity.
- An energy-efficient home. Many banks offer an interest rate discount for an EPC label A or B, and the lower energy bill counts towards your affordability.
- Compare. Request at least three quotes, or use a mortgage broker. The differences between banks can run up to half a percentage point.
Work it out yourself on every property
On every property page on ikzoek.immo you'll find a monthly repayment calculator: adjust your deposit, the term and your household income, and you'll immediately see the estimated monthly repayment, the property tax and the home insurance, and whether you stay within the one-third norm. That way you search based on what you can afford, not on what the asking price happens to be.