This will depend which software you are using.
For all submissions received and successfully validated by HMRC an electronic confirmation is issued with a code (IRMARK) which confirms the submission has been received and also that it hasn't changed since you submitted it.
Also, for Verification Requests, you'll be sent a Verification Reply detailing the subcontractors' tax rates.
This is available if you use HMRC's free CIS Online software but may be handled differently by commercial software. You'll need to check with your software supplier.