A vizsgadíjat ma kötelező befizetni.

Because -t is the accusative ending in Hungarian. It marks the direct object of the verb.

• vizsgadíj = exam fee
• vizsgadíjat = the exam fee (as the thing being paid)

In this sentence, the exam fee is the thing that must be paid, so it appears in the accusative.

A is the definite article, meaning the.

So:

• A vizsgadíjat = the exam fee

Hungarian has two forms of the definite article:

• a before most consonants
• az before vowels

For example:

• a könyv = the book
• az iskola = the school

Yes. Hungarian very often forms compound nouns as a single word.

• vizsga = exam
• díj = fee
• vizsgadíj = exam fee

This is very normal in Hungarian. English often writes these as two words, but Hungarian commonly combines them.

Ma means today.

Its position is natural here and gives today noticeable importance:

• A vizsgadíjat ma kötelező befizetni.

This suggests something like It is today that the exam fee must be paid or The exam fee must be paid today.

Hungarian word order is flexible, and placement often reflects focus or what is being highlighted, not just grammar.

Kötelező means obligatory, mandatory, or required.

In this sentence it functions like an impersonal predicate:

• kötelező befizetni = it is mandatory to pay

So the whole sentence expresses obligation, similar to English must.

You may also see kötelező used before a noun:

• kötelező olvasmány = required reading

But here it stands on its own and combines with an infinitive.

In the present tense, Hungarian often omits the verb to be (van) in sentences like this.

So:

• A vizsgadíjat ma kötelező befizetni. literally works like
• The exam fee today obligatory to-pay.

But natural English is:

• The exam fee must be paid today.

This omission is very common in Hungarian when describing something in the present.

Because kötelező is followed by an action expressed as an infinitive.

• befizetni = to pay in / to pay

So:

• kötelező befizetni = it is mandatory to pay

This is a common Hungarian pattern:

• szabad bemenni = it is allowed to go in
• tilos dohányozni = it is forbidden to smoke
• nehéz megérteni = it is difficult to understand

Fizetni is the general verb to pay.

Befizetni is more specific. It often means to pay in, to submit a payment, or to pay an amount to an institution/account/office.

So in the context of fees, bills, school payments, or official payments, befizetni is very natural.

For example:

• fizetni a boltban = to pay in a shop
• befizetni a tandíjat = to pay the tuition fee
• befizetni a számlát = to make the payment for the bill

Here, befizetni fits because an exam fee is the kind of official payment you submit.

The prefix be- often has the idea of in or into, but with verbs it can become more abstract.

With befizetni, it suggests paying money into a system, to an office, to an account, or as an official payment.

So while you do not always need to translate be- literally, it helps explain why befizetni feels more specific than plain fizetni.

Hungarian often leaves the subject unstated when the sentence is meant generally or impersonally.

This sentence does not explicitly say who must pay. It simply states the rule or requirement:

• The exam fee must be paid today.

This style is common in notices, regulations, school instructions, and formal announcements.

Yes, a very common alternative would be:

• A vizsgadíjat ma be kell fizetni.

This also means The exam fee must be paid today.

The difference is mostly one of phrasing:

• kötelező befizetni = it is obligatory/mandatory to pay
• be kell fizetni = it has to be paid / must be paid

Both are natural, but kötelező can sound slightly more formal or rule-like.

A helpful breakdown is:

• A vizsgadíjat = the exam fee (object)
• ma = today
• kötelező = mandatory / required
• befizetni = to pay in / to pay

So the structure is roughly:

• [object] + [time] + [obligation word] + [infinitive]

Very literally:

• The exam fee today obligatory to pay.

Natural English:

• The exam fee must be paid today.