The Irish Rugby Football Union has introduced regulations which will mean only one non-Irish qualified player is allowed to play across the 15 positions for Ulster, Leinster and Munster.
Under the new regime, if an overseas player such as Ruan Pienaar played for Ulster, then Leinster and Munster would be unable to sign foreign scrum-halves.
The objective is to deliver at least two experienced Irish players in all 15 field positions for the Ireland team.
The changes will take effect in 2013.
The IRFU say it is attempting to strike a long-term balance between success for the Ireland team and the needs of the provincial teams in terms of the recruitment of quality overseas playing talent.
After consultation with boards of the provincial teams and the national team management, the new policy has now been agreed by the union.
From the 2013-14 season onwards all future provincial injury replacement players will have to be eligible for selection for Ireland.
The new rules will not apply to Connacht as they recently commenced a new programme of structural and performance development agreed with the IRFU.
The IRFU statement said the policy changes would ensure that "Irish qualified players who have progressed through the provincial academy systems will see greater opportunities for professional game time experience, allowing both the IRFU and provinces to deliver the maximum amount of value for the 2.5m euro that is invested annually across the four provincial academies".
It continued: "The overall objective of the new policies is that there will be a minimum of two Irish qualified players per position playing in the Heineken Cup and RaboDirect Pro 12 as first choice selections."
In the event of two provinces both wanting to have a foreign player in the same position, then, as now is the case, the IRFU's professional contracts group will arbitrate and decide which province has the greater need.
The rule changes state that the three provinces will not be able to renew non-Irish players contracts after the 2012/13 season but pre-existing player deals which extend into the new period will be allowed to continue.
The new rules will be "position specific" so if the provinces want to re-sign a foreign player, he will have to play in a different position.
The foreigner rule is five players per province so if one of the provinces opted to have only three imports, the other two would still be restricted to five each.