According to official CAT website, CAT 2018 will be conducted on Nov 25, 2018 ( Sunday ).
It has also been mentioned that a detailed notification for the CAT 2018 "may be released in July / August 2018".
Last year, the notification was released in July and IIM Lucknow had conducted the entrance exam and the registration had started on August 9. Last year the CAT examination fees was Rs 900 for SC, ST and PWD applicants and for general category, it was Rs 1800.
The results for the CAT are usually released during the second week of January. Last year about 2.31 lakh candidates had registered for the entrance test.