NEC3 contracts do not specifically talk about or deal with Earned Value(EV) therefore any such requirements needs to be outlined with in Works Information that this is a requirement/expectation for the Contractor to carry out and how they should do this. This will include what project baseline this should be measured against, and very importantly the rules around if and when that baseline can be changed (for things like compensation events or major logic change).
The NEC3 “baseline” is the latest Accepted Programme, which is what change (compensation events) will be measured against. This will be separate from a “performance measurement baseline” to measure EV against. So you should have the original baseline to maintain (see below) and the Accepted Programme - which reflects reality. Next programme submitted with actuals/revised forecasts will use the last Accepted Programme as the baseline to report against in terms of change.
I get the principle of EV but in practice it is very difficult to measure in our construction industry. You are comparing your current performance against an original programme that probably didn’t have everything in it that should have been there, logic changes, level of detail changes and obviously compensation events would not have been there. Writing rules about how and when the EV baseline can be changed is key to a project that should ensure the effort required to maintain it is reflective of the benefit/information it is feeding out.