1. “Not advisable” evaluates an action
Shouldn’t helps say that an action is a poor choice: it is not advisable for you, us or them to do it. The speaker advises against the action rather than reports that the person is not doing it.
The advice can concern a present choice, a future plan or habitual behaviour. A reference to tomorrow does not require will before shouldn’t. Adding a reason helps explain the recommendation.
You shouldn't send the message now. You sound angry.
You shouldn't send the message now. You sound angry.
This advises waiting; it does not describe a message that is already not being sent.
We shouldn't take the last bus tomorrow. It arrives too late.
We shouldn't take the last bus tomorrow. It arrives too late.
Tomorrow establishes a future plan; shouldn’t take itself does not change.
2. The sentence frame: no do, no -s, no extra to
Put the subject first, followed by shouldn’t or should not and then the base form: go, buy, leave, be. With he, she and it, do not add -s to should or to the next verb.
Negation is already contained in shouldn’t / should not. Don’t, doesn’t and didn’t are unnecessary here. The base verb directly after should does not take to.
Subject + shouldn’t / should not + base verb + …
- subject / S —
- The grammatical subject: who or what the clause is about; the verb agrees with it. In The book was written, the book is the subject, although someone else does the action.
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
- V1 / base form —
- The base verb without to: work, go, be.
She shouldn't leave the door open.
She shouldn't leave the door open.
With she, still use leave, not leaves.
They should not put wet cups on the books.
They should not put wet cups on the books.
Not follows should; put is in its base form.
3. Full and contracted forms
Shouldn’t and should not express the same basic negation. The contraction is common in conversation and informal messages; the full form also suits emphasis or a more restrained written tone.
The full form alone does not turn advice into law. Do not call shouldn’t incorrect merely because it is informal. In an exercise specifying a particular form, meet that requirement; in other answers, both versions are acceptable.
The English contraction needs an apostrophe before t: shouldn’t. The straight apostrophe and typographic apostrophe are two ways to write the same word.
You shouldn't pay before you check the price.
You shouldn't pay before you check the price.
The contracted form suits advice to someone you know.
We should not promise a date before we check the plan.
We should not promise a date before we check the plan.
The full form is natural in a written recommendation to a team.
4. Not just you: be, have and a second action
I shouldn’t gives advice to yourself; we shouldn’t expresses a shared decision; he / she / they shouldn’t gives advice about another person or group. The construction is not restricted to addressing you.
An adjective needs be before it: shouldn’t be rude. If the next verb have means possession or having something, write have after shouldn’t, not has.
The “no to” rule concerns the link between should and the next verb. After an ordinary verb, to may be needed: shouldn’t forget to call. Prepositional to also remains, for example go to work.
I shouldn't be rude to the new neighbour.
I shouldn't be rude to the new neighbour.
Rude is an adjective; shouldn’t be links it to the subject.
He shouldn't have so many meetings in one day.
He shouldn't have so many meetings in one day.
Have is an ordinary verb here; this is not a construction about the past.
We shouldn't forget to call the host.
We shouldn't forget to call the host.
Forget follows shouldn’t without to; to call depends on forget and is correct.
5. Advice, the need to refrain and lack of necessity
You shouldn’t bring a large bag evaluates bringing a large bag as a poor idea. You don’t have to bring a bag / You don’t need to bring a bag means a bag is optional: you can bring one if you want. That is a different meaning, not another way to say it is inadvisable.
Mustn’t / must not expresses the need not to do something. It can convey a prohibition but also a very strong personal warning. The absence of a sign or law does not make mustn’t ungrammatical.
Shouldn’t often sounds softer than mustn’t, but is not always weak advice: it can express a serious moral judgement. Its strength depends on the situation, wording and tone. If an exercise requests should, another modal may fail to meet the task while remaining correct English.
You shouldn't bring a large bag. There is very little space.
You shouldn't bring a large bag. There is very little space.
The speaker recommends a more practical choice.
You don't need to bring a bag. We can give you one.
You don't need to bring a bag. We can give you one.
Lack of necessity neither prohibits nor criticises the action.
You mustn't tell Jo about the party. It is a surprise!
You mustn't tell Jo about the party. It is a surprise!
A strong personal warning without a law or official prohibition.
People shouldn't laugh at someone for making a mistake.
People shouldn't laugh at someone for making a mistake.
Shouldn’t can express a firm judgement about unacceptable behaviour.
6. Advice or expectation: context decides
One form has several uses. The delivery shouldn’t take long can mean the delivery is unlikely to take much time: this is an expectation, not advice to the delivery. Do not determine the meaning from shouldn’t alone.
For negative advice, look for an action the speaker recommends avoiding and the reason for that recommendation. This is the use practised in this lesson. The expectation meaning is included only for comparison.
Shouldn’t have + past participle often evaluates an action already in the past. That is a separate topic. Here we discuss current choices and future actions with shouldn’t + base verb.
The queue shouldn't be long at nine. The shop has just opened.
The queue shouldn't be long at nine. The shop has just opened.
The speaker predicts the length of the queue rather than advises it to change.
We shouldn't join that queue. Our bus leaves in five minutes.
We shouldn't join that queue. Our bus leaves in five minutes.
The speaker advises the group not to spend time queuing.
7. Advice you can use in conversation
A useful response names a specific action rather than evaluates the person as a whole. After negative advice, you can add a reason or a positive option with should. This makes the message clear and gives the listener a next step.
You can begin with Maybe you shouldn’t… or I think we shouldn’t… for a less categorical tone. These are options, not required parts of the construction. I don’t think you should… also naturally expresses similar advice; if a task explicitly requires shouldn’t / should not, that phrase does not demonstrate the target form.
You do not need to copy the model word for word in your own answers. Preserve the situation, correct negative advice and appropriate tone; personal details can be invented.
Maybe you shouldn't book that room. It is far from the station.
Maybe you shouldn't book that room. It is far from the station.
Maybe softens the presentation, and the reason explains the advice.
We shouldn't rush. We should read the instructions first.
We shouldn't rush. We should read the instructions first.
The first part discourages rushing; the second offers a specific alternative.
Common mistakes
Incorrect:You shouldn't to buy it.
Correct:You shouldn't buy it.
Immediately after shouldn’t, use buy without to.
Incorrect:She shouldn't sends the email.
Correct:She shouldn't send the email.
After the modal, send has no -s ending, even with she.
Incorrect:We don't should wait outside.
Correct:We should not wait outside.
Should forms its negative without auxiliary do; put not after should.
Incorrect:He shouldn't is late.
Correct:He shouldn't be late.
Base be is needed instead of finite is.
Incorrect:They should not leaving yet.
Correct:They should not leave yet.
This simple construction needs leave, not leaving.