Unfortunately there is no facility to view your client’s submission in either the previous agent account or the new agent services account (ASA) once signed up for Making Tax Digital.
If it is simply to view the return in question and the figures you should be able to check the details on your compatible software package in which you filed the clients VAT return. If it is to check and confirm receipt of the VAT return the client should be able to do this via their business tax account (BTA). If they do not have one they would need to create one and enrol for the service.
From your post it would appear that you are a tax agent and this and future posts may be more appropriate to the HMRC Agent Forum.
Please follow the following instructions to join the HMRC Agent Forum:
You will need to send the following identity information:
Your first name and surname
Confirmation of your work email address
The name of your firm/organisation
The name of your professional body/ies
Your professional body registration number/reference
Once you have sent your email, the forum team will be in touch to confirm your acceptance. After this, you will have access to HMRC’s new and improved Agent Forum, including all live and previous posts on Agent related issues.