Mustn't and needn't

The two halves differ by a preposition: não tens de against não podes.

Words you will need3

They appear in this topic’s examples and exercises and are new at this point on the learning path.

proibirto forbid
deixarto leave, to let
estacionarto park

Practise as flashcards

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Understand

Remembernão ter de allows the leaving, não poder forbids the doing.

Signal words: não tens de
não podes
não precisas de
não é preciso

The form

How the forms are built

Each row gives the meaning first, then the form in Portuguese. The colours show what changes from one form to the next.

stem (regular) stem (irregular) person ending negation

I must not	(eu) não posso
you must not	(tu) não podes
he / she must not, you must not	(ele / ela / você) não pode
we must not	(nós) não podemos
you must not, plural and formal	(vós) não podeis
they must not, you must not (plural)	(eles / elas / vocês) não podem
I do not have to	(eu) não tenho de
you do not have to	(tu) não tens de
he / she does not have to, you do not have to	(ele / ela / você) não tem de
we do not have to	(nós) não temos de
you do not have to, plural and formal	(vós) não tendes de
they do not have to, you do not have to (plural)	(eles / elas / vocês) não têm de
you must not	não podes
you should not, you must not	não deves
you do not have to	não tens de
you need not	não precisas de
there is no need	não é preciso
it is forbidden	é proibido

The rules one by one

The form this topic is about

não ter de is the absence of an obligation.
Não tens de vir.You do not have to come.
não poder is a prohibition.
Não podes abrir essa porta.You must not open that door.
não dever sits between them: advice or ban, by tone.
Não deves dizer isso ao Paulo.You should not tell Paulo that.
ter and precisar take de, poder and dever take nothing.
Não precisas de partir cedo.You need not leave early.

Example sentences

Não podes fumar aqui.You must not smoke here.

Não tens de responder já.You do not have to answer right away.

Não é preciso voltar a ligar.There is no need to call back.

1 more example sentences

É proibido deixar a chave fora.Leaving the key outside is forbidden.

The trap English speakers fall into

Watch out

The English pair is close enough that the wrong one comes out under pressure, and here the wrong one says the opposite. Não tens de tocar nisso is permission to leave it alone; a prohibition needs não podes tocar nisso. If the de is there, nobody is being forbidden anything.

Wrong:Não tens de tocar nisso! (as a prohibition)

Right:Não podes tocar nisso!

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The full explanation

Read it all · about 1 min

Two English sentences that sound alike mean opposite things: « you don't have to » is no obligation, « you mustn't » is a prohibition. Portuguese splits them with two constructions.

Forbidden is não podes or não deves. Not necessary is não tens de or não precisas de.

There is a shape here worth noticing, because it is the quickest way to keep the two apart. The two that mean « no obligation » both carry de; the two that mean « forbidden » carry nothing. Não tens de and não precisas de against não podes and não deves. The preposition marks the harmless half.

Não é precisois the impersonal form for what is not neededé proibidothe one for what is forbidden

The verbs on this page, in every form: ser · ter · dizer · abrir · deixar · partir · responder · precisar