Only half of of the new regional health service bodies set up under the controversial NHS reforms will be fully ready to start work when the changes come into effect on Monday.
Just 106 of the 211 Clinical Commissioning Groups (CCGs) are "fully authorised", said NHS England.
The other 105 still have conditions attached to their authorisation which means some of their decisions will have to be signed off or approved by NHS England - the overarching body formally known as the NHS Commissioning Board.
Conditions are placed on CCGs if they do not meet in full the 119 criteria set at a national level.
But NHS England said that every community in England is now covered by one of 211 CCGs - even if some of the bodies do have conditions attached to their authorisation.
The new groups are led by GPs and other clinicians who will take on responsibility for commissioning local hospital, community health and mental health services. The groups will be responsible for £65 billion of the £95 billion NHS commissioning budget.
Dame Barbara Hakin, national director for commissioning development at NHS England, said: "I am delighted that more than three quarters of CCGs will begin work with either full authorisation, or with only a small number of conditions. Local clinicians are enthusiastic about the opportunity to shape healthcare on behalf of their local communities, and that enthusiasm has shone through during the authorisation process.
"As we have always anticipated, CCGs are at differing levels of maturity, so some do need intensive support, while others are already well advanced. NHS England is fully committed to providing collaborative help and support for all CCGs."