Tagliabue originally said he would step down in July, but will now leave the job on August 18 in order to ensure a smooth handover to his successor.
A search firm hired to find his replacement will now discuss candidates with the 32 team owners before the shortlist is drawn up.
A final decision is expected to be made when the owners meet to discuss the issue in July.
The search for a replacement to NFL commissioner Paul Tagliabue is gathering steam with owners set to whittle down potential candidates to a short list of three to five.
