not supposed to

supposed to

1. Intended, expected, or believed to do something. This new software is supposed to make things a lot more efficient, but I find it so confusing that everything is taking me twice as long! We're supposed to arrive around 3 PM, assuming our flights aren't delayed.
2. Required or obligated to do something. I was supposed to be home an hour ago—my parents are going to kill me! Please don't distract him, he's supposed to be cleaning his room.
3. Allowed or permitted to do something. (Chiefly used in questions and negative constructions.) You're not supposed to go in there! Are you sure you're supposed to be in here?
See also: supposed
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

(It's) not supposed to.

 and (Someone's) not supposed to.
a phrase indicating that someone or something is not meant to do something. (Often with a person's name or a pronoun as a subject. See the examples.) Fred: This little piece keeps falling off. Clerk: It's not supposed to. Bill: Tom just called from Detroit and says he's coming back tomorrow. Mary: That's funny. He's not supposed to.
See also: not, supposed
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
See also:
References in periodicals archive ?
Dr Letsa said journalists were not supposed to serve any political party, but the people of Ghana, and called for balanced reportage at all times.
"There are those who even say that am a girl, I am not supposed to be a comedian and the mentality that we are not supposed to be paid more than a male comedian just pisses me off," she said.
"We're not supposed to be a bank," complained Maine Township Trustee Susan Sweeney, who voted against it and argued for reducing the tax levy.
Queen Elizabeth was reportedly not supposed to be proclaimed queen, but she is now known as Britain's longest-reigning monarch.
'Hindi ba dapat doon na tayo papunta [Are we not supposed to be heading that direction]?
The leader was not supposed to keep a cell phone with him, jail authorities were not supposed to allow him to keep the phone or facilitate his contacts in a foreign country.
Summary: New Delhi, [India] June 28 (ANI): Who knew that the iconic song 'Khaike Paan Banaras Wala' was not supposed to be a part of Amitabh Bachchan starrer 'Don'.
Iranian Foreign Minister Mohammad Javad Zarif said the 2015 nuclear deal between Tehran and world powers was not supposed to address the country's banking problems, adding that such issues should be seen in the context of the Financial Action Task Force (FATF).
'So if we are not supposed to receive contributions and if we collect funds from the public, they laughed at us, so why is it okay for them to do so?' he asked.
Becoming pregnant, preparing for parenthood and becoming a family is not supposed to be nine months of anxiety.
When asked about rumors of Imran Khan's third marriage, Billawal said that he was not supposed to talk about "Chach" [Imran Khan] but the media always trapped him by asking question about PTI chairman.
For instance we were not supposed to do all our obligations immediately after JPOA but it takes a long time for them to carry out the commitments one by one.
This innovation ensures that labels that are not supposed to be dispensed onto a pack remain on the backing strip and are wound together with the backing strip.
Is it true that you are not supposed to wash mushrooms?
They said they did not know the reasons why they were not supposed to let her enter Greece and that she would be given detailed information by the Greek Liaison Office in Skopje.