Buying a home together: how couples run KALP and split the costs

All amounts in the worked examples are made up and rounded.

When you buy a home together, the bank runs KALP (kvar att leva på, roughly “left to live on”) on the household, not on each of you separately. Two incomes give more room, but the calculation also becomes more sensitive to what happens if one of them disappears. Here we walk through a calculation similar to the bank’s for a couple, two ways to share the money and what happens when one income drops.

How KALP works with two incomes

The principle is the same as for one person. The bank starts from the household’s net income and subtracts:

Interest at the stress rate. Not your actual rate but a higher stress rate (kalkylränta), often around 6–7 %. It differs between banks.
Amortisation. Under the amortisation requirement, 2 % per year when the loan-to-value ratio is above 70 %. See the 2026 mortgage rules.
Housing cost. The housing association fee or operating costs.
Living costs for two adults. Banks generally use the Swedish Consumer Agency’s (Konsumentverket) calculated amounts per household type, see what is KALP.
Other loans. Both people’s student loans (CSN), car loans and other credit count.

What remains is the margin. If it is positive the household passes; many banks want to see a buffer above zero. The exact figures vary between banks, so treat BoKalk’s calculation as preparation, not as the bank’s answer.

Worked example: Anna and Bo buy a flat

Anna and Bo are made up. Anna takes home SEK 28,000 a month after tax, Bo SEK 22,000. They are looking at a housing association flat (bostadsrätt) for SEK 4,000,000 with a monthly fee of SEK 4,000. The down payment is 10 %, so SEK 400,000, and the loan is SEK 3,600,000. In the example they share the loan and the interest equally, have no capital income and pay enough tax to use the whole tax reduction.

Item	Per month
Net income, Anna	SEK 28,000
Net income, Bo	SEK 22,000
Household net income	SEK 50,000
Interest at 6.5 % stress rate on SEK 3,600,000, after the tax reduction	−SEK 13,905
Amortisation 2 % per year	−SEK 6,000
Housing association fee	−SEK 4,000
Living costs, two adults (assumed, rounded)	−SEK 14,000
Margin	+SEK 12,095

Interest at the stress rate is SEK 19,500 a month before the tax reduction for interest (ränteavdrag). That is SEK 234,000 a year, so SEK 117,000 per person. According to the Swedish Tax Agency (Skatteverket, in Swedish), the tax reduction is 30 % on the part of a capital deficit that is up to SEK 100,000 per person per year, and 21 % on the part above (checked on 2026-10-09). That is SEK 33,570 per person per year, for both SEK 5,595 a month. The living cost is a rounded assumption; use Konsumentverket’s current amounts for your household when you run your own numbers. Read more in KALP: how the bank decides whether you can afford the mortgage.

How to split the down payment and the monthly cost

There is no right answer, only different models. Two common ones:

Equal shares. Each of you pays half of everything. Easy to keep track of, but heavier for the person who earns less.

In proportion to income. Anna earns 56 % of the household income (28,000 of 50,000) and Bo 44 %. The same shares are used for the down payment and the monthly cost.

With an actual interest rate of 3.5 % (made up), the real housing cost is: interest SEK 10,500, amortisation SEK 6,000 and fee SEK 4,000, a total of SEK 20,500 a month before the interest deduction.

	Equal shares	By income
Down payment, Anna	SEK 200,000	SEK 224,000
Down payment, Bo	SEK 200,000	SEK 176,000
Housing cost per month, Anna	SEK 10,250	SEK 11,480
Housing cost per month, Bo	SEK 10,250	SEK 9,020

Often you have not saved the same amount. Say Anna has SEK 250,000 and Bo SEK 150,000 for the down payment. Together that is still SEK 400,000, but the question of how ownership should be divided becomes more important. This article gives no legal advice on ownership shares, cohabitation agreements or prenuptial agreements. If you have put in different amounts, get help from a lawyer before you sign.

If one income drops

Parental leave, illness, unemployment or studies can lower one of the incomes for a period. Assume Bo’s net income falls from SEK 22,000 to SEK 14,000 a month. The amount is made up; what you actually receive depends on your benefits, so check with Försäkringskassan (the Social Insurance Agency) or your unemployment fund (a-kassa).

At the stress rate, household income becomes SEK 42,000 while costs stay at SEK 37,905. The margin shrinks from +SEK 12,095 to +SEK 4,095. The calculation still works in the example, but the margin is SEK 8,000 smaller.

In everyday life they pay the actual rate. With SEK 20,500 in housing costs before the interest deduction and SEK 14,000 in living costs, this is what remains:

	Both incomes	Bo’s income lowered
Household net income	SEK 50,000	SEK 42,000
Housing cost (actual rate)	−SEK 20,500	−SEK 20,500
Living costs	−SEK 14,000	−SEK 14,000
Left per month	SEK 15,500	SEK 7,500

It still works, but the buffer is halved. If they split by income, the shares move too: Bo then accounts for 14,000 of 42,000, one third, and pays about SEK 6,830 of the housing cost while Anna pays about SEK 13,670. Talk this through before the purchase, and run the scenario before you decide how high you can bid.

Both of you see the same property in BoKalk

In BoKalk you can invite a partner to your household, whether or not you have a subscription. You then share a household profile and joint properties, according to BoKalk’s terms. When one of you adds a property, the other sees the same property with the same details, and you can compare the calculations without sending screenshots. If the household has an active subscription, the partner shares that too. The app is not yet sold in the App Store or Google Play; this section describes how the feature is meant to work once it is.

BoKalk runs a calculation similar to the bank’s KALP, but it does not replace the bank’s assessment. Use it to prepare for the conversation with the bank and with each other.

Frequently asked questions

Does the bank run KALP on both incomes when we buy together?

Yes. When you apply for the loan together, the bank starts from the household’s combined net income and subtracts housing costs at the stress rate, amortisation and living costs for two adults. BoKalk runs a similar calculation; the bank’s own assessment may come out differently.

Do we have to split the monthly cost equally?

No, that is your choice. Common models are equal shares or shares in proportion to income. How ownership should be divided is a legal question this article does not give advice on.

What happens if one of us loses income?

The household’s margin shrinks. In the example in the article, the margin at the bank’s stress rate, counted after the tax reduction, falls from +SEK 12,095 to +SEK 4,095, while the money left after actual housing costs before the interest deduction and living costs falls from SEK 15,500 to SEK 7,500 a month. Run that scenario before you decide on a price level.

Buying your first home, step by step · What is KALP?

Christoffer, founder BoKalk