Learn Hardcore Dutch: Dat is natuurlijk geen probleem; we hebben inderdaad genoeg tijd. - That is of course no problem; we indeed have enough time.

If you said Dat is niet een probleem, it would sound unusual here and would suggest something like “That is not one problem (but maybe something else)”, or be used to contrast with another noun:
Dat is niet een probleem maar een uitdaging. – That is not a problem but a challenge.

For “no problem” as a fixed expression, Dutch almost always uses geen probleem, not niet een probleem.

What is the nuance of natuurlijk here, and can I move it in the sentence?

Natuurlijk literally means naturally, but in everyday speech it often means “of course”.

Here, Dat is natuurlijk geen probleem roughly means “That’s of course no problem” and sounds friendly and reassuring.

You can move natuurlijk to different positions, with small nuance changes:

Dat is natuurlijk geen probleem. – neutral, very common.
Natuurlijk is dat geen probleem. – a bit more emphatic: Of course that’s no problem.
Dat is geen probleem, natuurlijk. – adds a slightly afterthought / reassuring tone: That’s no problem, of course.

All are grammatically correct; the default is exactly the version you have.

Why does the sentence start with Dat is and not Het is?

Both dat and het can mean “that/it”, but:

Dat points to a specific thing or situation that was just mentioned or is clear from context:
Dat is geen probleem. = That is no problem (that thing we’re talking about).
Het is more neutral and is often used for general states, weather, time, or impersonal expressions:
Het is koud. – It is cold.
Het is een probleem. – It is a problem (in general).

In your sentence, the speaker is clearly referring back to something specific (“that thing you just mentioned”), so Dat is natuurlijk geen probleem is more natural.
Het is natuurlijk geen probleem is not wrong, but it sounds less pointing/explicit about the earlier context.

What does inderdaad add to the meaning of we hebben inderdaad genoeg tijd?

Inderdaad means “indeed / actually / in fact”, and it usually:

Confirms or agrees with something that was said before, or
Emphasizes that something is truly the case.

So:

We hebben genoeg tijd. – We have enough time. (plain statement)
We hebben inderdaad genoeg tijd. – We do indeed have enough time. / We actually have enough time.

It can imply agreement or reassurance, e.g. responding to someone who wondered whether there was enough time.

Why is the word order we hebben inderdaad genoeg tijd and not something else? Where does inderdaad go?

Dutch likes to keep adverbs like inderdaad in the “middle field” of the sentence, typically between the subject and the rest of the verb phrase:

Subject – finite verb – (some adverbs) – objects / complements

So:

We hebben inderdaad genoeg tijd. = standard, natural order.

Other possibilities:

Inderdaad hebben we genoeg tijd. – Inderdaad is pulled to the front for emphasis (Indeed, we have enough time.).
We hebben genoeg tijd inderdaad. – possible, but sounds more like an afterthought or extra comment.

The version you have is the most neutral and common in ordinary speech and writing.

What is the difference between genoeg tijd and voldoende tijd?

Both mean “enough time”, but there’s a nuance:

genoeg tijd – very common, neutral, everyday language.
We hebben genoeg tijd. – We have enough time.
voldoende tijd – a bit more formal, sometimes used in written or official contexts, or when stressing sufficiency in a somewhat measured way.
Er is voldoende tijd gepland. – Sufficient time has been scheduled.

You can usually swap them, but genoeg sounds more informal and conversational.

Could you replace the semicolon with something else in Dutch, and how is the semicolon used here?

Yes, you could use other punctuation:

Dat is natuurlijk geen probleem. We hebben inderdaad genoeg tijd.
Dat is natuurlijk geen probleem, want we hebben inderdaad genoeg tijd.

The semicolon in Dutch works much like in English:

It links two closely related independent clauses.
It keeps them visually connected without using a conjunction like want (because).

So Dat is natuurlijk geen probleem; we hebben inderdaad genoeg tijd. connects:

the reassurance (that’s no problem), and
the reason (we have enough time),

without explicitly saying want (because).

Why is probleem in the singular (geen probleem) instead of geen problemen?

This is mostly idiomatic:

Geen probleem is a fixed, very common way to say “no problem” (as in that’s okay / that’s all right).
Geen problemen is also correct, but its meaning is more literal: no problems (not any problems), often used in contexts like issues, errors, or obstacles.

For example:

Dat is geen probleem. – That’s no problem (it’s fine, don’t worry).
We hebben geen problemen met de planning. – We have no problems with the planning.

In your sentence, the polite reassuring phrase is expected, so geen probleem is the natural choice.

Is this sentence formal or informal? Could I use it in an email?

The sentence is neutral and polite and works in both informal and many semi-formal situations:

It’s fine in spoken conversation with colleagues, friends, or customers.
It’s also fine in many emails, especially if the general tone is friendly rather than very official.

Example in an email:

Dat is natuurlijk geen probleem; we hebben inderdaad genoeg tijd.
That is of course no problem; we do indeed have enough time.

If you wanted it slightly more formal, you might write:

Dat is geen probleem; we hebben voldoende tijd.
Dat vormt geen probleem, want er is voldoende tijd.

But your original sentence is fully acceptable in most professional contexts.

How does the present tense here relate to the future? In English we might say “That will be no problem.”

Dutch often uses the present tense where English might use “will”:

Dat is geen probleem; we hebben genoeg tijd.
Literally: That is no problem; we have enough time.
Meaning: That will be no problem; we will have enough time.

Future meaning is clear from context (you’re talking about a future plan/appointment). You can use the future tense:

Dat zal geen probleem zijn; we zullen genoeg tijd hebben.

But in everyday Dutch, the present tense version is more natural and less heavy unless you need to stress the futurity or add extra emphasis.

Can I say Dat is geen probleem natuurlijk instead of Dat is natuurlijk geen probleem?

Yes, that is possible, but the nuance changes slightly:

Dat is natuurlijk geen probleem. – natuurlijk is integrated into the core statement; feels neutral and fluent.
Dat is geen probleem, natuurlijk. (with a comma, usually) – natuurlijk feels more like an afterthought or a little reassurance added at the end, similar to:
That’s no problem, of course.

Without a comma, Dat is geen probleem natuurlijk is still understandable, but usually people either put natuurlijk earlier (the standard way) or clearly separate it with a comma in speech (intonation) and writing.

What is the difference in nuance between natuurlijk and inderdaad in this sentence?

They both express agreement/confirmation, but they do different things:

natuurlijk (of course) signals that something is obvious or expected from the speaker’s point of view:
Dat is natuurlijk geen probleem. – That’s of course no problem (it’s obviously fine).
inderdaad (indeed / actually) confirms or supports what has been said or assumed:
We hebben inderdaad genoeg tijd. – We do indeed have enough time (that’s really the case).

So the sentence structure is:

natuurlijk: softens and reassures (of course it’s fine),
inderdaad: confirms the factual reason (we really do have enough time).