Avmeldingen mottas før avmeldingsfristen.

Because Norwegian usually marks definiteness by adding it to the end of the noun.

• en avmelding = a cancellation / a deregistration
• avmeldingen = the cancellation / the deregistration

So -en here is the definite singular ending. The base noun is avmelding.

It is singular.

You can tell because:

• en avmelding = singular, indefinite
• avmeldingen = singular, definite
• avmeldinger = plural, indefinite
• avmeldingene = plural, definite

So this sentence is talking about one specific cancellation.

Mottas is the present passive form of å motta (to receive).

A useful pattern is:

• å motta = infinitive
• mottar = present active
• mottas = present passive

So:

• Vi mottar avmeldingen = We receive the cancellation
• Avmeldingen mottas = The cancellation is received

This -s passive is very common in formal Norwegian, especially in rules, instructions, and administrative language.

Because Norwegian can form the passive in two main ways:

1. -s passive
   
   • Avmeldingen mottas
2. bli-passive
   
   • Avmeldingen blir mottatt

Both can often be translated with English is received.

In this sentence, the -s passive is used. It is especially common in formal written language, and it sounds natural in notices, terms, deadlines, and regulations.

Yes, grammatically you could. But it sounds less natural in this kind of formal deadline sentence.

For administrative or official style, Norwegian often prefers the -s passive:

• Avmeldingen mottas før avmeldingsfristen.

The version with blir mottatt is possible, but it can sound a bit heavier or less standard in this context.

Very often, Norwegian would also make the requirement even clearer with må:

• Avmeldingen må mottas før avmeldingsfristen.

It is a compound noun, which is extremely common in Norwegian.

It is made from:

• avmelding = cancellation / deregistration
• frist = deadline
• -en = definite singular ending

So:

• avmeldingsfrist = cancellation deadline
• avmeldingsfristen = the cancellation deadline

Norwegian often combines nouns into one single word where English would use several words.

That -s- is a linking element used in many Norwegian compounds.

So:

• avmelding + frist becomes avmeldingsfrist

This -s- does not usually have a separate meaning by itself. It just helps the compound sound and look natural. English speakers often find this strange at first, but it is very normal in Norwegian compound formation.

Other compounds also use linking sounds or letters, while some do not. Unfortunately, this is something you often learn word by word.

Because Norwegian often uses the present tense for:

• general rules
• scheduled events
• official conditions
• instructions

So mottas is present tense, but the sentence is understood as a rule or requirement: this is what must be true before the deadline.

English does something similar sometimes:

• Payment arrives before the deadline
• The form is submitted by Friday

So even though the action may happen later, the present tense is normal here.

Før means before.

Here it introduces a time expression:

• før avmeldingsfristen = before the cancellation deadline

In this sentence, før is followed by a noun phrase, not a full clause.

Compare:

• før avmeldingsfristen = before the deadline
• før fristen går ut = before the deadline expires

So in your sentence, før works like a preposition introducing the deadline phrase.

Because Norwegian main clauses normally follow the V2 rule: the finite verb comes in the second position.

Here the structure is:

• Avmeldingen = subject
• mottas = finite verb
• før avmeldingsfristen = time expression

So the verb is in second position, which is exactly what Norwegian expects in a normal declarative main clause.

Both nouns here are common gender nouns, so they take en in the indefinite singular.

• en avmelding
• en frist

That gives the definite forms:

• avmeldingen
• fristen

When they appear inside a compound, the last noun determines the gender of the whole compound. So:

• en avmeldingsfrist
• avmeldingsfristen

Because Norwegian often expresses things more compactly through:

• compound nouns
  
  • avmeldingsfristen
• suffixes for definiteness
  
  • avmeldingen
• -s passive forms
  
  • mottas

So a short Norwegian sentence can contain a lot of grammatical information inside single words. This is very typical of formal written Norwegian.