How to calculate dynamic SLA Performance % based on each HR Case's Resolution SLA target?

[Satyam123]

Hi Community,

I’m looking for guidance on enhancing an existing Average Resolution Time report for completed HR Cases.

Current Report

• Table: Task SLA

• Task Type: HR Case

• SLA Target: Resolution

• Stage: Completed

• Assignment Group: Applicable Billing groups

• Currently showing Average Business Elapsed Time

Requirement

I need to calculate SLA Performance % for each case based on its own applicable Resolution SLA target:

SLA Performance % = Actual Resolution Time ÷ Applicable SLA Target × 100

For example:

• 8 hrs SLA / 6 hrs actual = 75%

• 12 hrs SLA / 10 hrs actual = 83.3%

• 16 hrs SLA / 18 hrs actual = 112.5%

The SLA target should be dynamic per case/priority, rather than using a single fixed SLA value.

Cases with Performance > 100% should be highlighted in red.

The final report should allow performance to be viewed by Assignment Group, while ensuring each case is evaluated against its respective Resolution SLA target.

Question: What is the recommended ServiceNow approach to achieve this? Should this be done using a calculated field, database view, scripted field, or another reporting solution?

Thanks in advance!