Partial reverse charge

In service Tax Return, Point A10 of construction service, need to select ST paid as a Service Receiver (SR) "Yes" and below that need to mention "Yes" for Partial RCM as a  SR.

after that, you need to mention the Exemption notifaction i  Point A11 and select appropriate Notification no. for Construction services and
Need to mention the abatement notification in Point no A12 and select correct notification no. for such abatement
after that, in Part B1 as a SR, mention the amount of taxable i.e.50% of partial RCM in point no. B1.6 and also mention the abatement amount in point B1.11

Then you can see the total tax liability and pay such ST and file the return after successfully generation of XML file.