Na de belastingaanslag kunnen invorderingskosten volgen.

Because Dutch main clauses usually follow the verb-second (V2) rule.

In this sentence, Na de belastingaanslag is placed first for emphasis or as the starting point of the sentence. Once that happens, the finite verb must come next:

• Na de belastingaanslag = first element
• kunnen = finite verb in second position
• invorderingskosten = subject
• volgen = infinitive at the end

So the basic idea is:

• normal order: Invorderingskosten kunnen na de belastingaanslag volgen.
• with the time phrase first: Na de belastingaanslag kunnen invorderingskosten volgen.

This is a very common Dutch word-order pattern.

Because kunnen is a modal verb. In Dutch main clauses, when you use a modal verb such as:

• kunnen = can / may
• moeten = must
• willen = want
• mogen = may
• zullen = will / shall

the second verb usually goes to the end in the infinitive form.

So here:

• kunnen = finite/modal verb
• volgen = infinitive

That is why you get:

• kunnen ... volgen

Because the subject is invorderingskosten, which is plural.

• singular: de kost kan volgen
• plural: de kosten kunnen volgen

Since invorderingskosten means collection costs or recovery costs, it is grammatically plural, so the verb must also be plural:

• invorderingskosten kunnen

Belastingaanslag is a compound noun:

• belasting = tax
• aanslag = assessment, levy, tax bill, official amount imposed

In many contexts, belastingaanslag means something like:

• tax assessment
• tax bill
• tax notice

It does not mean attack here, even though aanslag can mean that in other contexts. In tax language, it has a technical administrative meaning.

Because Dutch very often forms compound nouns by joining words together into a single word.

So:

• belasting
  • aanslag → belastingaanslag
• invordering
  • kosten → invorderingskosten

This is extremely normal in Dutch. English often writes similar ideas as separate words, but Dutch usually combines them.

It is another compound noun:

• invordering = collection, recovery, enforcement of payment
• kosten = costs

So invorderingskosten literally means:

• collection costs
• costs of recovery
• enforcement costs

In context, it refers to extra costs that may be charged when a tax debt is being collected.

Because Dutch, like English, often uses no article with an indefinite plural noun.

Compare:

• De invorderingskosten = the collection costs
• Invorderingskosten = collection costs / some collection costs

In this sentence, the meaning is general and indefinite: collection costs may follow. So no article is needed.

Na means after.

Here it introduces a time sequence:

• Na de belastingaanslag = After the tax assessment / after the tax bill

So the sentence is saying that one thing can happen after another thing.

This is a very common preposition in Dutch:

• na het eten = after the meal / after eating
• na school = after school
• na de vakantie = after the holiday

It expresses possibility, not ability.

So in this sentence, kunnen is best understood as something like:

• may
• can
• might

depending on how natural the English translation is in context.

It does not mean that the costs are physically able to do something. It means that such costs may occur or can follow as a possible consequence.

Yes, but in a slightly broader administrative sense.

Volgen often means to follow, but in official or formal language it can also mean:

• to come after
• to occur afterwards
• to ensue

So invorderingskosten volgen means that collection costs may follow afterwards or be added later.

It is definitely formal/administrative Dutch.

Clues include:

• belastingaanslag
• invorderingskosten
• the impersonal, official style

A more everyday explanation might be something like:

• Na de belastingaanslag kunnen er extra kosten bijkomen.

That sounds less technical. The original sentence sounds like something from a tax office letter, government website, or legal/financial text.

Yes. That is also grammatical.

The difference is mainly in focus:

• Na de belastingaanslag kunnen invorderingskosten volgen.
  Focuses first on the timing: after the tax assessment
• Invorderingskosten kunnen na de belastingaanslag volgen.
  Focuses first on invorderingskosten

Both are correct. Dutch is flexible in moving elements to the front, but when something other than the subject comes first, the finite verb still has to stay in second position.