The ECB's move, which will see changes made to the C and G Trophy and the totesport League One-day competition, is designed to ensure potential England players receive more One-day "exposure" ahead of an international call-up.
Since its introduction in 1963, what is now the C and G has, under various sponsors, always been a straight knock-out competition.
But from 2006, apart from the final which will still be staged at Lord's in August, the C and G will take place over the first half of the season.
Then the totesport League, set to revert from 45 overs to the old 'Sunday League' maximum of 40 overs per side will take place.
Both competitions will feature coloured clothing and white balls throughout as has long been the case in international One-day cricket.
In a move reminiscent of the later years of the now defunct Benson and Hedges Cup, the C and G will feature several rounds of early season Limited-Overs matches.
The 18 first-class counties will be divided into two 'conferences' - north and south - with Scotland joining the former and Ireland the latter. The winner of the northern conference will play the winner of the southern conference in the final.
The totesport League is expected to begin in mid-July and will continue to be played in two divisions - with games scheduled on Sundays, Bank Holidays or played flood-lit in mid-week.
Counties will play eight games - against teams in their division either home or away.
But instead of the current three-up and three-down system of promotion and relegation, it will be two in each direction.
However, "in order to provide an appropriate end-of-season climax," the final match of the new domestic season will be a play-off between the third-placed team in the second division and the seventh in the first to decide which county will take their place in the top flight the following campaign.
Meanwhile the County Championship, England's domestic first-class competition remains largely unchanged although in future prize money will reward the top three teams in the first division and the winners only in the second.
The Twenty20 Cup, inaugurated in 2003 and already updated for 2005, will be kept as it is too - the ECB saying: "It is intended group matches will continue to be played in a 15-day 'window'.
But the Board added it would be looking at the "potential commercial benefits of including two overseas teams in the Twenty20 Cup".
The ECB also announced their intention to "urge counties to contract players for longer periods of the year (preferably 12 months)".
And from 2006 potential Test players will get another chance to shine when England A play two first-class matches against the tourists.