Betjeningsevnen øker i den grad medlåntakerens inntekt øker.

Norwegian very often builds long compound nouns, so betjeningsevne is one compound word rather than two separate words.

Here it is made up of:

• betjening = servicing, handling, repayment service
• evne = ability, capacity

So betjeningsevne means something like repayment capacity or ability to service a loan.

The ending -n in betjeningsevnen makes it definite singular:

• en betjeningsevne = a repayment capacity
• betjeningsevnen = the repayment capacity

Norwegian usually shows definiteness by adding an ending to the noun, instead of using a separate word like the.

I den grad is a fairly formal expression meaning:

• to the extent that
• insofar as
• as

In this sentence, it connects the two ideas and shows a proportional relationship:

• the repayment capacity increases
• to the extent that the co-borrower’s income increases

So it is not just giving extra information; it is showing that one change depends on the size of the other change.

This expression is more formal and written-sounding than everyday spoken Norwegian.

Because it is a genitive form, meaning the co-borrower’s.

Start with:

• medlåntaker = co-borrower
• medlåntakeren = the co-borrower

Then Norwegian adds -s for possession:

• medlåntakeren + s = medlåntakerens

So medlåntakerens inntekt means the co-borrower’s income.

This is very common in Norwegian:

• mannen → mannens
• brukeren → brukerens
• læreren → lærerens

Because Norwegian normally writes compounds as a single word.

So:

• med = with, co-
• låntaker = borrower

Together they form medlåntaker = co-borrower or joint borrower.

This is a major difference from English. English often uses separate words or hyphens, but Norwegian usually prefers one compound word.

Because when a noun is preceded by a possessor, the noun itself is usually left in the indefinite form in Norwegian.

So Norwegian says:

• mannens bil = the man’s car
• barnets navn = the child’s name
• medlåntakerens inntekt = the co-borrower’s income

Even though the meaning is definite in English, Norwegian does not usually make the second noun definite here.

So inntekt is correct, not inntekten.

Because there are really two clauses, and each clause has its own verb:

• Betjeningsevnen øker = the repayment capacity increases
• medlåntakerens inntekt øker = the co-borrower’s income increases

Norwegian keeps the verb in both parts. English can sometimes compress this kind of idea into something like the more X increases, the more Y increases, but Norwegian often states both verbs explicitly.

So the repetition is normal and grammatical.

Yes. The meaning is very close to a jo ... desto ... pattern, which also expresses proportional change.

For example, a similar idea could be expressed as:

• Jo mer medlåntakerens inntekt øker, desto mer øker betjeningsevnen.

That means roughly the same thing.

The difference is mostly one of style:

• i den grad sounds more formal, administrative, or financial
• jo ... desto ... can sound a bit more straightforward and transparent to learners

So the original sentence is not wrong at all; it is just somewhat formal.

Because Norwegian often uses the present tense for general truths, rules, or standard relationships.

This sentence is not necessarily describing one specific event happening right now. It is stating a general principle:

• if the co-borrower’s income goes up, repayment capacity goes up accordingly

That is why øker is used in the present tense in both clauses.

Yes, but it sounds quite formal and typical of banking, finance, or official written language.

A native speaker would understand it immediately, but in everyday speech they might choose something simpler or more direct.

So this sentence is natural in the right context, especially if it comes from:

• a loan calculator
• bank information
• mortgage guidelines
• financial advice text

It has a slightly bureaucratic tone rather than a casual spoken tone.