Learn Hardcore Portuguese (Portugal): Logo que eu terminar o relatório, vou descansar. - As soon as I finish the report, I am going to rest.

Because Portuguese is using the future subjunctive here: logo que eu terminar = as soon as I finish / once I have finished (referring to the future).

In European Portuguese, when you talk about a future event after certain conjunctions (like quando, logo que, assim que, se, enquanto, depois que, etc.), you normally use the future subjunctive, not the simple present or the simple future.

Logo que eu terminar o relatório → future subjunctive (uncertain, depends on something happening in the future)
Not: Logo que eu termino o relatório (this sounds wrong in European Portuguese when referring to the future)
Not: Logo que eu terminarei o relatório (future indicative cannot go directly after logo que in this meaning)

So eu terminar here is:

tense/mood: future subjunctive
reason: required by logo que when it refers to a future action

How can I tell that terminar here is the future subjunctive and not an infinitive?

Formally, you can’t tell from the verb form alone – for this verb, the future subjunctive and the personal infinitive are identical in some persons:

Future subjunctive (1st person singular): (quando) eu terminar
Personal infinitive (1st person singular): (para) eu terminar

So what tells you the difference is the word before it:

After conjunctions that take the future subjunctive (like quando, logo que, assim que, se, enquanto), a future time is usually expressed with the future subjunctive.
- Logo que eu terminar o relatório… → future subjunctive
After prepositions (like para, sem, por), you are more likely to have the personal infinitive.
- Para eu terminar o relatório… → personal infinitive

Here logo que is a conjunction of time, so learners are expected to recognize that eu terminar is in the future subjunctive.

Could I say Logo que eu termine o relatório instead of Logo que eu terminar o relatório?

In European Portuguese, for a future action after logo que, the future subjunctive (terminar) is the standard, natural choice.

Logo que eu terminar o relatório, vou descansar. ✅ (normal in Portugal)
Logo que eu termine o relatório, vou descansar. ⭑ (sounds odd / not standard in Portugal in this future-time meaning)

Some learners are influenced by Spanish (which uses present subjunctive in similar structures) or by descriptions based on Brazilian Portuguese. In European Portuguese grammar, the rule is:

Future reference + quando / logo que / assim que / se → future subjunctive

So for Portugal, stick with logo que eu terminar for “as soon as I finish (in the future)”.

What does logo que literally mean, and how is it different from quando and assim que?

logo que literally combines logo (right away, immediately) + que (that), and as a fixed expression it means “as soon as”.
assim que also means “as soon as” and is very close in meaning to logo que.
quando means “when” and can be broader / less immediate.

Nuances:

Logo que eu terminar o relatório, vou descansar.
→ As soon as I finish the report, I’ll rest. (immediate sequence)
Assim que eu terminar o relatório, vou descansar.
→ Very similar; many speakers would use it interchangeably with logo que.
Quando eu terminar o relatório, vou descansar.
→ When I finish the report, I’ll rest. (could be slightly less emphatic about immediate succession, but in practice often overlaps)

All of them, when referring to a future event, regularly take the future subjunctive in European Portuguese.

Is the logo in logo que the same logo that can mean “therefore / so”?

It is the same word, but used in different fixed expressions with different meanings:

logo que
- Conjunction of time → “as soon as”
- Logo que eu terminar… = As soon as I finish…
Sentence-initial logo,
- Adverb / connective, more formal → “therefore / thus”
- Ele não estudou; logo, não passou no exame.
  → He didn’t study; therefore he didn’t pass the exam.
logo by itself in time expressions
- Can mean “soon / in a bit”:
  - Vou sair logo. = I’ll leave soon.

So yes, it’s the same lexical word, but in logo que it’s part of a fixed expression meaning “as soon as”.

Can I drop the subject pronoun eu and say Logo que terminar o relatório, vou descansar?

Yes. European Portuguese is a pro‑drop language, so subject pronouns are often omitted when the verb form already tells you the person:

Logo que terminar o relatório, vou descansar. ✅
Logo que eu terminar o relatório, vou descansar. ✅

Both are correct and natural. Including eu may:

Add a bit of emphasis on I (as opposed to someone else).
Sound slightly more explicit or careful in speech or writing.

But grammatically, both options are fine.

Could I put the clauses in the opposite order: Vou descansar logo que eu terminar o relatório?

Yes, that is completely natural:

Logo que eu terminar o relatório, vou descansar.
Vou descansar logo que eu terminar o relatório.

Both mean the same thing. The only small differences are:

With the time clause first, there is often a slight emphasis on the condition/time: As soon as I finish… (then) I’ll rest.
With the main clause first, you start by stating your intention, then add the condition: I’ll rest, as soon as…

In writing, the sentence-initial subordinate clause is usually followed by a comma, as in the original. When the subordinate clause comes after the main clause, a comma is usually not used:

Logo que eu terminar o relatório, vou descansar. (comma)
Vou descansar logo que eu terminar o relatório. (no comma in modern usage)

Why is it vou descansar instead of the simple future descansarei?

In modern spoken European Portuguese, the periphrastic future ir + infinitive (vou descansar) is far more common than the simple future (descansarei) for everyday future plans:

Vou descansar. → extremely common in speech
Descansarei. → grammatically correct, but often sounds more formal, distant, or written‑style

Both can appear in this sentence:

Logo que eu terminar o relatório, vou descansar. ✅ (normal spoken style)
Logo que eu terminar o relatório, descansarei. ✅ (more formal / literary, but still correct)

So vou descansar expresses the same basic future meaning, but sounds more natural in most day‑to‑day conversation.

Should I translate vou descansar as “I will rest” or “I’m going to rest”?

Both are possible translations, depending on style and context:

Literal structure: ir (to go) + descansar (to rest) → I am going to rest.
But English often uses “will” for future plans too, so “I’ll rest” is also a good translation.

In context, you might choose:

“As soon as I finish the report, I’m going to rest.”
“As soon as I finish the report, I’ll rest.”

The key idea (future rest after finishing) is the same.

Why is there a definite article: o relatório? Could we say just terminar relatório?

In Portuguese, a definite, specific object normally takes the definite article:

o relatório = the report (a specific one that both speaker and listener know about)

Saying terminar relatório without o would sound very odd in this context. Dropping the article is only natural in certain special cases (titles, headlines, some fixed expressions, after some prepositions in set phrases, etc.), but not here.

If you wanted a more generic meaning (not a specific report), you might use something like:

terminar relatórios = finish reports (in general)
terminar um relatório = finish a report (one, not specified)

Here the speaker clearly has one specific report in mind, so o relatório is the normal choice.

Could I say assim que instead of logo que here?

Yes, in European Portuguese logo que and assim que are very close in meaning when they introduce a time clause with a future reference:

Logo que eu terminar o relatório, vou descansar.
Assim que eu terminar o relatório, vou descansar.

Both mean “As soon as I finish the report, I’ll rest.”

Both also normally take the future subjunctive (eu terminar) in this future-time use. The choice between them is often just a matter of personal or regional preference, with logo que perhaps a bit more frequent for many speakers.

Why is it descansar and not descansar‑me here? Isn’t “to rest” reflexive in some languages?

In Portuguese, descansar is normally not reflexive when it means to rest:

Vou descansar. = I’m going to rest.
Preciso de descansar. = I need to rest.

The reflexive form descansar‑se exists but is:

Rare in the sense of simply resting one’s body.
More commonly used in other meanings or fixed expressions, e.g. descansar em alguém (to rely on / rest on someone), where em is essential.

So in this sentence, vou descansar is exactly how a native speaker would say “I’m going to rest”, without any reflexive pronoun.

How would this sentence change if we were talking about the past instead of the future, e.g. “As soon as I finished the report, I rested”?

For past time, you no longer use the future subjunctive. Instead you switch to past indicative forms:

Logo que acabei o relatório, descansei.
→ As soon as I finished the report, I rested.

or with terminar:

Logo que terminei o relatório, descansei.

Structure:

logo que
- pretérito perfeito do indicativo (e.g. acabei / terminei)
main clause also usually in pretérito perfeito (descansei)

So the future subjunctive eu terminar is specific to future reference after conjunctions like logo que; with past reference, you just use the normal past tense.