The tax credit conversation around the One Big Beautiful Bill Act has been dominated by lawyers and policy analysts. That's appropriate, because the statutory mechanics of ITC and PTC eligibility are genuinely complex. But there's a parallel conversation that hasn't happened yet. One that belongs to engineers. Under the OBBBA, new wind and solar projects must either begin construction on or before July 4, 2026, or be placed in service by December 31, 2027, to remain eligible for the ITC and PTC. And the 5% safe harbor (the method that allowed developers to qualify by simply incurring 5% of total project costs) has been largely eliminated for projects over 1.5 MW AC. What remains is the Physical Work Test: tangible, documentable, defensible evidence that real construction has begun. That's an engineering problem, not a legal one.
