Learn Hardcore Portuguese (Portugal): Quando tivermos feito voluntariado durante um ano inteiro, havemos de olhar para trás com orgulho. - When we have done volunteering for a whole year, we will surely look back with pride.

Tivermos feito is the future subjunctive of ter plus the past participle feito (from fazer). Together, tivermos feito means “we have done (in the future)” – a kind of future perfect.

In Portuguese, time clauses introduced by quando that refer to the future normally use the future subjunctive, not the present or future indicative, especially in European Portuguese:

Quando tivermos feito voluntariado…
= When we have done volunteer work…

The idea is: at the moment in the future when our volunteer work of one whole year is already completed. So the action in this clause finishes before the action in the main clause (havemos de olhar).

Using a simple future indicative like quando faremos is incorrect here.
Using quando fizermos voluntariado (see below) is possible, but it slightly changes the nuance.

Exactly what tense and mood is tivermos, and how is it formed?

Tivermos is the future subjunctive of the verb ter.

To form the future subjunctive of a verb in Portuguese, you generally take the third person plural of the preterite (past) and remove the -am ending:

ter → preterite: tiveram → remove -am → tiver-
Future subjunctive: quando eu tiver, quando tu tiveres, quando ele/ela tiver, quando nós tivermos, quando vocês/eles tiverem

So tivermos is “we (will) have” in a future, uncertain or conditional context (after quando, se, logo que, assim que, etc.).

Then you add the past participle feito (from fazer) to build a compound tense:

quando tivermos feito = when we have done (by that future point)

Why do we say fazer voluntariado instead of using a specific verb like voluntariar-se?

In European Portuguese, the most natural and common way to say “to do volunteer work / to volunteer” is:

fazer voluntariado

This treats voluntariado as a noun (“volunteering / volunteer work”) and fazer as the light verb “to do”.

Alternatives exist but are less neutral:

voluntariar-se – exists but tends to sound more formal or bureaucratic, and is less common in everyday European Portuguese.
ser voluntário – means “to be a volunteer”, focusing more on the role/status than on the activity.

So:

Fiz voluntariado durante um ano.
= I did volunteer work for a year. (most idiomatic)

is more natural than:

Voluntariei-me durante um ano. (grammatical but odd in many contexts)

What is the difference between Quando tivermos feito voluntariado durante um ano inteiro and Quando fizermos voluntariado durante um ano inteiro?

Both are possible, but the nuance is slightly different:

Quando tivermos feito voluntariado durante um ano inteiro…
– Focuses on the completion of the whole year of volunteering.
– Very close to English “When we have done volunteer work for a whole year…” (future perfect idea).
Quando fizermos voluntariado durante um ano inteiro…
– Focuses more on doing the volunteer work in that period.
– Feels a bit more general; it can be understood as “when we do volunteer work (over) a whole year”.

In practice, in this specific sentence, both are acceptable; tivermos feito makes the “one entire year completed” idea a bit clearer and more explicit.

Is durante necessary in durante um ano inteiro, or could we just say um ano inteiro?

Both are possible:

durante um ano inteiro
um ano inteiro

The difference is small:

durante explicitly highlights duration, a bit like English “for an entire year”.
Without durante, um ano inteiro still clearly indicates the length of time, and is also very natural.

So you could say:

Quando tivermos feito voluntariado um ano inteiro, havemos de olhar para trás com orgulho.

and it would still sound natural in European Portuguese. Durante just makes the duration slightly more explicit and is very common.

What exactly does havemos de mean, and how is it different from vamos or olharemos?

Havemos de + infinitive is a periphrastic future construction. In this sentence:

havemos de olhar ≈ we will look / we are bound to look / we’re sure to look

Nuance:

It often adds a feeling of eventuality, expectation or moral certainty, sometimes slightly less immediate than vamos.
It can sound a bit more literary or old-fashioned, but in European Portuguese it still appears in everyday speech, especially in expressions like:
- Havemos de conseguir. – We’ll manage (eventually).
- Hás de ver. – You’ll see.

Comparisons:

Havemos de olhar para trás… – we will (surely/eventually) look back…
Vamos olhar para trás… – we are going to look back… (more immediate/planned future)
Olharemos para trás… – simple future; can sound slightly more formal or written in many contexts in EP.

In your sentence, havemos de gives a tone of confident expectation: once that year is over, we’re bound to look back with pride.

Could we replace havemos de olhar with vamos olhar or olharemos without changing the meaning too much?

Yes, both alternatives are grammatically correct, with small nuances:

Quando tivermos feito voluntariado durante um ano inteiro, vamos olhar para trás com orgulho.
– Very natural, everyday speech. Feels more like a plan/intention.
Quando tivermos feito voluntariado durante um ano inteiro, olharemos para trás com orgulho.
– Correct and clear; in European Portuguese it often sounds more formal or written.
Quando tivermos feito voluntariado durante um ano inteiro, havemos de olhar para trás com orgulho.
– Slightly literary or expressive, emphasising eventual, almost inevitable future.

All three can translate as “we will look back with pride”, but havemos de has that extra flavor of “we’re bound to / we’re sure to”.

What does para trás add to olhar? Could we just say olhar atrás or omit para?

Olhar para trás is the standard expression meaning “to look back”, both literally and figuratively.

olhar – to look
para – towards
trás – back/behind

So olhar para trás = look towards the back → look back.

Alternative forms:

olhar atrás – also possible, but olhar para trás is much more idiomatic in this sense.
You cannot simply drop para and say olhar trás – that is wrong.

In a metaphorical sense (thinking about the past), olhar para trás is the normal expression:

Um dia vamos olhar para trás e rir.
= One day we’ll look back and laugh.

Why is the subject pronoun nós not written? How do we know the subject is “we”?

Portuguese is a pro-drop language, which means subject pronouns are often omitted when the verb ending already shows the subject.

tivermos → 1st person plural (we)
havemos → 1st person plural (we)

These specific verb forms can only refer to nós in standard Portuguese, so you don’t need to say nós explicitly:

(Nós) tivermos
(Nós) havemos de olhar

Adding nós is possible if you want to emphasise it:

Quando nós tivermos feito voluntariado durante um ano inteiro, nós havemos de olhar para trás com orgulho.

but it’s usually unnecessary and can sound heavy unless you want to stress we (in contrast to others).

Is this sentence more formal, neutral, or colloquial in European Portuguese?

Overall, the sentence is neutral, but certain choices give it a slightly literary / elevated tone:

tivermos feito – fully standard; typical in both spoken and written language when talking about the future with quando.
havemos de olhar – grammatically normal, but slightly more literary or expressive than vamos olhar. In some contexts it can sound old-fashioned; in others, just a bit poetic or emphatic.
Vocabulary like voluntariado, um ano inteiro, olhar para trás com orgulho is neutral and common.

So it would fit well in a motivational speech, written text, or semi-formal conversation, and can also be spoken naturally, especially in Portugal.