T20 Blast Finals Day will take place on Saturday 3 October in the hope games might be played in front of a crowd.
Prime Minister Boris Johnson said last month that, following a renewed Covid-19 threat, plans to allow fans to attend sporting fixtures were being shelved until 1 October.
That will come too late for the England and Wales Cricket Board's new red-ball competition, the Bob Willis Trophy.
The date for the five-day final at Lord's will be 23-27 September.
But there are hopes the four T20 Blast quarter-finals on Thursday 1 October could be played in front of limited crowds - and that fans would then also be in attendance for the 18th T20 Finals Day in Birmingham two days later, for what will now be the 2020 domestic season's concluding fixture.
The ECB will continue to follow government guidance on exactly when crowds might return following two successful red-ball trials in July at The Oval and Edgbaston over the weekend prior to the start of the Bob Willis Trophy.
The new T20 Finals Day date will be a month later than the original date of Saturday 5 September, chosen prior to the lockdown in March following the escalation of the coronavirus pandemic.
And it is a week later than a proposal to end the season on Saturday 26 September, which had been earmarked when the 18 English first-class counties first began serious negotiations in July on how it should be completed.
Live streams a success - Harrison
"It promises to be a thrilling climax to the season," said ECB chief executive Tom Harrison. "The prestige of a Lord's final for the Bob Willis Trophy will provide an even greater incentive and it's pleasing to see so many watching the high-class entertainment via the enhanced live streams the counties have invested in.
"Finals Day at Edgbaston will also ensure the men's county cricket finishes the season on a high.
"The fact we've been able to get so much domestic cricket played this summer owes to the collaborative efforts of the county network and their willingness to find a way to get the game on in the safest way possible.
"There will be many more challenges ahead, but the unity and spirit shown during this summer has been a tribute to the county network."
How will the T20 Blast work?
The T20 Blast will begin on Thursday 27 August when holders Essex host Middlesex in a full programme concluding with Yorkshire's televised home clash with Nottinghamshire.
The 10-match qualifying stage has been split into the same North, Central and South groups currently being used in the Bob Willis Trophy.
- North Group: Derbyshire, Durham, Lancashire, Leicestershire, Notts, Yorkshire
- Central Group: Birmingham Bears, Glamorgan, Gloucestershire, Northants, Somerset, Worcestershire
- South Group: Essex, Hampshire, Kent, Middlesex, Surrey, Sussex
Thursday 27 August
- Essex v Middlesex (Chelmsford, 14:00)
- Gloucestershire v Northamptonshire (Bristol, 14:00)
- Kent v Hampshire (Canterbury, 14:00
- Glamorgan v Worcestershire (Sophia Gardens 18:30)
- Derbyshire v Leicestershire (Leicester, 18:30)
- Durham v Lancashire (Chester-le-Street, 18:30)
- Yorkshire v Notts, Headingley 18:35)
Friday 28 August
- Sussex v Surrey (Hove, 14:00)
- Birmingham Bears v Somerset (Edgbaston, 18:30)