Mi pagos tuj, se la fakturo estas ĝusta.

Pagos is the future tense form of pagi (to pay).

• mi pagas = I pay / I am paying
• mi pagos = I will pay

So Mi pagos tuj means I will pay immediately / right away.

In this sentence, the payment will happen later, after the condition is met, so the future ending -os is the natural choice.

This is a very common question. In Esperanto, just like in English, a se clause often uses the present tense when talking about a future possibility.

So:

• se la fakturo estas ĝusta = if the invoice is correct

Even though the whole situation may be in the future, Esperanto does not need estos here. The idea is: if the invoice turns out to be correct / if it is correct.

You could sometimes see a future form in other contexts, but in a simple conditional sentence like this, estas is normal and natural.

Tuj means immediately, right away, or at once.

So:

• Mi pagos tuj = I’ll pay immediately
• Mi pagos tuj, se... = I’ll pay right away, if...

It gives a sense of no delay.

La is the Esperanto definite article, meaning the.

• fakturo = an invoice / invoice
• la fakturo = the invoice

Here it refers to a specific invoice that both speaker and listener understand from context.

Unlike English, Esperanto uses only one article form: la. It does not change for gender, number, or case.

Because ĝusta is describing la fakturo, and la fakturo is the subject of estas.

In Esperanto, predicate adjectives after esti usually do not take -n.

So:

• La fakturo estas ĝusta. = The invoice is correct.

Compare that with a direct object:

• Mi kontrolas la ĝustan fakturon. = I am checking the correct invoice.

There, ĝustan gets -n because it modifies a direct object.

In Esperanto, adjectives end in -a.

So:

• ĝusta = correct
• bona = good
• granda = big

Since fakturo is singular, ĝusta also stays singular. If the noun were plural, the adjective would also become plural:

• la fakturo estas ĝusta = the invoice is correct
• la fakturoj estas ĝustaj = the invoices are correct

Adjectives agree with nouns in number and case.

It is a conditional clause introduced by se, which means if.

The sentence has two main parts:

• Mi pagos tuj = the main clause
• se la fakturo estas ĝusta = the condition

So the structure is:

I will pay immediately, if the invoice is correct.

You could also reverse the order:

• Se la fakturo estas ĝusta, mi pagos tuj.

That means the same thing.

Yes. Esperanto word order is fairly flexible, although some orders sound more neutral than others.

These are all possible:

• Mi pagos tuj, se la fakturo estas ĝusta.
• Se la fakturo estas ĝusta, mi pagos tuj.
• Tuj mi pagos, se la fakturo estas ĝusta.
  (more emphasis on tuj)

The most neutral order is usually the original one or the version with the se clause first.

Yes, fakturo is a normal Esperanto noun meaning invoice or bill.

Like many Esperanto words, it is based on an international root. The ending -o marks it as a noun:

• faktur- = root
• -o = noun ending

So fakturo literally has the standard Esperanto noun form.

A rough pronunciation is JHOOS-tah.

More specifically:

• ĝ sounds like the j in judge
• u sounds like oo in food
• a sounds like ah

So ĝusta is approximately JHOOS-tah.

Also, every Esperanto letter has one consistent pronunciation, which makes reading much easier once you learn the alphabet.

Not exactly.

• nun = now
• tuj = immediately / right away

Tuj focuses on speed or lack of delay, not necessarily the exact present moment.

So Mi pagos tuj means something like:

• I’ll pay right away
• I’ll pay immediately

It may happen very soon, but the key idea is promptness, not simply now.

Not quite. Se means if, not as soon as.

So the sentence means:

• I’ll pay immediately, if the invoice is correct.

That is a condition.

If you wanted as soon as, Esperanto would use a different expression, such as tuj kiam:

• Mi pagos tuj, kiam la fakturo estos ĝusta.
• or more naturally depending on context, another phrasing about the invoice being corrected or confirmed

So se is specifically conditional: if.

Because Esperanto usually expresses tense through verb endings, not separate helper words.

For pagi (to pay):

• pagas = present
• pagis = past
• pagos = future
• pagus = conditional
• pagu = imperative/jussive
• pagi = infinitive

So instead of saying a separate word for will, Esperanto changes the verb itself:

• I will pay → Mi pagos

This is one of the regular and convenient parts of Esperanto grammar.