In case of any difficulty in accessing the ACES Application or in filing the ST-3 returns, the assessees can seek help of the ACES Service Desk by sending e-mail to aces.servicedesk@icegate.gov.in or calling up National Toll-free number 1800 425 4251. In general, the Service Desk functions on any working day from Monday to Friday between 9 AM and 7 PM & on Saturdays between 9 AM to 2.30 PM. But to help the assessees file their returns, it will remain open from 9 AM and 7 PM on all Saturdays and closed holidays till