According to an official communication issued by the Home Ministry, the IPS officers must complete at least “two years of Central experience at the rank of SP, DIG or equivalent level to be eligible for empanelment as IG or equivalent at the Centre. The new provision will apply to IPS officers of the 2011 batch onwards.”

New norms for IPS Officers seeking IG rank
New Delhi: The Ministry of Home Affairs has made it mandatory for IPS officers to complete a minimum two-year central deputation at the SP or DIG level to qualify for empanelment as Inspector General (IG) at the Centre.
This new rule applies to IPS officers from the 2011 batch onward. It is intended to ensure they gain sufficient central government experience before taking on senior leadership roles.
According to an official communication issued by the Home Ministry, the IPS officers must complete at least "two years of Central experience at the rank of SP, DIG or equivalent level to be eligible for empanelment as IG or equivalent at the Centre. The new provision will apply to IPS officers of the 2011 batch onwards."
(...being updated)