Når først omleveringen er umulig, vælger kunden prisafslaget.

Here når først means something like once or once it is the case that.

• når on its own often means when
• først adds emphasis and gives the sense of once / once it has become clear that

So Når først omleveringen er umulig is not just a simple time expression. It means:

• once replacement is impossible
• once it has been established that replacement cannot be done

This use is especially common in formal or legal-style Danish.

Because Danish main clauses follow the verb-second rule.

The sentence starts with the subordinate clause:

• Når først omleveringen er umulig

That whole clause takes the first position. In the main clause, the finite verb must then come second, so you get:

• vælger = verb
• kunden = subject

So the structure is:

• Når først omleveringen er umulig, vælger kunden prisafslaget.

If there were no opening clause, it would be:

• Kunden vælger prisafslaget.

This is a very common Danish word-order pattern.

Omleveringen is the definite form of omlevering.

In this kind of legal or commercial context, omlevering means replacement, especially replacing a defective item with another one.

So:

• omlevering = replacement
• omleveringen = the replacement

This is a fairly formal word. In everyday speech, people might use simpler wording depending on the situation.

Both nouns are in the definite form:

• omleveringen = the replacement
• prisafslaget = the price reduction

Danish often uses the definite form when talking about a specific option, remedy, or concept that is understood from the context. In legal language, this is especially common.

Even if English might say something more general like replacement or a price reduction, Danish may still use the definite form because it refers to the specific remedy under discussion.

Prisafslag means price reduction or reduction in price.

In consumer-law language, it usually means that the buyer keeps the item but gets part of the money back because the item is defective or cannot be properly replaced.

So:

• prisafslag = price reduction
• prisafslaget = the price reduction

With vælger, Danish says literally chooses the price reduction, though in natural English you might often say opts for a price reduction.

Because omleveringen is a common-gender singular noun.

The adjective agrees with the noun:

• common gender singular: umulig
• neuter singular: umuligt
• plural/definite adjective forms often: umulige

Here the subject is:

• omleveringen

and omlevering is a common-gender noun, so the correct form is:

• omleveringen er umulig

Compare:

• En løsning er umulig
• Et bytte er umuligt

It is closer to once or when/if in the event that.

In formal Danish, especially in rules, instructions, or legal language, når can introduce a condition that English might translate as:

• when
• once
• if

The best English choice depends on style, not just grammar. In this sentence, once often captures the meaning best because it suggests that the impossibility has already been established.

In Danish, vælge can take a direct object without a preposition.

So:

• vælge prisafslaget = choose the price reduction

That is fully normal Danish grammar.

English sometimes prefers opt for in this kind of formal context, but Danish does not need an equivalent preposition here.

It is grammatical and natural, but it sounds formal and somewhat legal/administrative rather than conversational.

Words like:

• omleveringen
• prisafslaget

are typical of consumer law, contracts, complaint procedures, and official explanations of buyer rights.

In everyday conversation, a speaker might use simpler wording, depending on the context.

Because the sentence begins with a subordinate clause, followed by the main clause.

• Når først omleveringen er umulig = subordinate clause
• vælger kunden prisafslaget = main clause

In standard Danish writing, a comma is normally placed between those two parts. That helps mark the clause boundary clearly.