Learn Hardcore Hungarian: Ha muszáj, a főnöknek is szólni kell. - If it is necessary, you also have to tell the boss.

Literally, muszáj means something like “it is a must / it is necessary”.
A more “complete” version in your head could be: Ha muszáj (szólni) = If it’s necessary (to tell).

Hungarian very often drops anything that can be understood from context, so Ha muszáj on its own is a perfectly normal clause meaning “If (it’s) necessary / If we really have to.”

What exactly does muszáj mean, and how strong is it compared to must / have to / need to?

Muszáj expresses necessity or obligation. It’s close to:

must
have to
need to (in the strong sense: you really need to)

In everyday speech:

muszáj is quite strong: it implies that you don’t really have a choice.
It’s less formal than something like szükséges (necessary), but not slangy; it’s very common and natural.

So Ha muszáj is more like “If we really have to / If it can’t be avoided” than a neutral “If it is necessary.”

Why do we need kell if we already have muszáj? Don’t they both mean must?

They do both express necessity, but they belong to different clauses and play different roles.

Ha muszáj is the if-clause: “If (it is) necessary / If we really have to.”
… szólni kell is the main clause: “(then) it is necessary to tell / you must tell.”

So the structure is:

Ha muszáj,
a főnöknek is szólni kell.
= If it’s necessary, (then) one must also tell the boss.

You could rephrase with just kell and no muszáj:

Ha kell, a főnöknek is szólni kell.
(If it’s necessary, one must also tell the boss.)

Or with just muszáj and no kell:

Ha muszáj, a főnöknek is muszáj szólni.
(grammatical, but less natural than the original)

In normal Hungarian, it’s very common to have muszáj in the if-clause and kell in the main clause like in your sentence.

How does kell work here, and why is szólni in the infinitive?

Kell works like a modal verb expressing necessity, similar to must / have to.

The pattern here is:

[infinitive] + kell
→ szólni kell = (one) must tell

Szólni is the infinitive of szól (“to speak / to let someone know / to tell (someone)”).
The construction is impersonal: there is no explicit subject. It means:

(in general) you/we/one must tell (someone)

If you want to make the subject explicit, you add a personal ending to the infinitive:

Szólnom kell. – I must tell.
Szólnod kell. – You must tell.
Szólnia kell. – He/She must tell.
Szólnunk kell. – We must tell.

So szólni kell is the neutral, subjectless version: “(someone) has to tell / it has to be told.”

Why is it a főnöknek and not something like a főnököt?

Because Hungarian uses the dative case for the person you tell / say something to.

-nak / -nek is the dative ending: “to / for” someone
- a főnöknek = to the boss
-t is the accusative ending: direct object (whom/what you affect directly)
- a főnököt = the boss (as a direct object, e.g. “I see the boss / I hit the boss”)

With szólni in this sense (“to inform / to let someone know”), the pattern is:

szólni valakinek = to tell / let someone know
→ a főnöknek szólni = to tell the boss / to let the boss know

So a főnöknek is szólni kell literally means “it is necessary to tell also to the boss.”

What does is mean in a főnöknek is, and why is it after főnöknek?

Is means “also, too, as well, even”.

It always comes right after the word it modifies.
Here it’s attached to a főnöknek, so it means “the boss too / the boss as well / even the boss.”

So:

a főnöknek is szólni kell ≈ “you must also tell the boss”,
implying: not only someone else (e.g. colleagues), but the boss as well.

If you moved is:

A főnöknek szólni is kell.
Now is attaches to szólni and can suggest “you also need to tell (not just do other things)” — slightly different nuance.

So its position is important, and after főnöknek it clearly means that the boss is included in the list of people to be told.

Could the word order be A főnöknek is kell szólni? Would that change the meaning?

You can say A főnöknek is kell szólni, and it’s grammatical, but:

A főnöknek is szólni kell is more neutral and more common.
A főnöknek is kell szólni slightly highlights kell (the necessity) a bit more.

In everyday conversation, most speakers will naturally say:

Ha muszáj, a főnöknek is szólni kell.

If you say A főnöknek is kell szólni, you’re not really changing who or what; you’re just giving a bit more stress to the fact of obligation itself. For learning purposes, treat them as very close in meaning, and prefer szólni kell as the more typical word order.

Who is the subject here? How would I say “I must tell the boss”?

In a főnöknek is szólni kell, there is no explicit subject. It’s a generic, impersonal statement:

“(one) must also tell the boss / you/we have to tell the boss.”

To say “I must tell the boss” explicitly, you make the infinitive personal:

Nekem a főnöknek is szólnom kell. – I must also tell the boss.

You can drop nekem unless you want to emphasize “I”:

A főnöknek is szólnom kell. – I must also tell the boss.

Similarly:

A főnöknek is szólnod kell. – You must also tell the boss.
A főnöknek is szólnia kell. – He/She must also tell the boss.

What is the difference between szólni and mondani? Could we say a főnöknek is mondani kell?

Szólni and mondani overlap but are used differently.

Szólni (in this sense):

often means “to let someone know / to notify / to give a word to someone”
typical pattern: szólni valakinek = tell someone / give someone a heads-up
→ szólni a főnöknek = tell the boss / give the boss a word

Mondani:

means “to say / to tell (something)”
it almost always needs what you say (an object):
- mondani valamit valakinek = to say something to someone
  - Mondtam neki az igazat. – I told him the truth.

So:

a főnöknek is mondani kell sounds incomplete by itself, because we don’t know what you have to say.
More natural versions:
- A főnöknek is meg kell mondani (az igazat). – You must tell the boss (the truth) as well.
- A főnöknek is el kell mondani. – It must be told to the boss as well.

In your original sentence, szólni is perfect because the content is not specified; it’s just about informing the boss in general.

Is muszáj formal or informal? Are there more formal alternatives?

Muszáj is informal–neutral:

very common in everyday speech
fine in many written contexts that are not highly formal
slightly colloquial in tone, but not slang

More formal or neutral alternatives:

Ha szükséges, a főnöknek is szólni kell.
(If it is necessary, the boss must also be informed.)
Ha elengedhetetlen, a főnöknek is szólni kell.
(If it is indispensable, one must also tell the boss.)
Szükség esetén a főnöknek is szólni kell.
(In case of necessity, the boss must also be informed.)

But in everyday spoken Hungarian, Ha muszáj is completely natural.

Does Ha muszáj always need a comma after it?

When Ha muszáj comes at the beginning of the sentence as a separate clause, you normally do put a comma:

Ha muszáj, a főnöknek is szólni kell.

If you flip the order, you also use a comma before ha:

A főnöknek is szólni kell, ha muszáj.

In standard Hungarian punctuation, subordinate clauses (like ones introduced by ha = if) are usually separated from the main clause by a comma, whether they come first or second.

Can this sentence refer to the past or future, or is it only present?

With kell, the basic form is present / timeless, but the actual time often comes from context.

As it stands:
Ha muszáj, a főnöknek is szólni kell.
→ usually understood as present/general: If (ever) it’s necessary, one (then) has to tell the boss.

To make it clearly past, you change kell to its past form kellett:

Ha muszáj volt, a főnöknek is szólni kellett.
= If it was necessary, one had to tell the boss as well.

For a clear future meaning, you typically keep kell and add a future context word like majd:

Ha muszáj lesz, a főnöknek is szólni kell.
(If it will be necessary, one will also have to tell the boss.)
Ha muszáj, majd a főnöknek is szólni kell.
(If necessary, one will also have to tell the boss then.)

So the structure itself is flexible; time is usually clarified by additional words (like volt, lesz, majd) or by context.

Could you rephrase this in a more personal, everyday style?

Yes, some common, more personal versions:

Ha muszáj, szólok a főnöknek is.
– If necessary, I’ll tell the boss too.
Ha muszáj, szólj a főnöknek is.
– If necessary, tell the boss too. (addressing you)
Ha muszáj, szóljunk a főnöknek is.
– If necessary, let’s tell the boss too.

These keep the same idea but use personal forms of szólni instead of the impersonal szólni kell.