The Iranian parliament has approved the outline of a bill that will allow the government to implement the nuclear deal.
According to the official IRNA news agency, the approval allows Tehran to withdraw from the imposed limits on its nuclear development programme if world powers do not lift sanctions.
The final approval for the measure is expected later this week.
Iran is expected to start reducing its nuclear activities on 18 October to meet the requirements of the International Atomic Energy Agency (IAEA). The day is referred to as Adoption Day in the timeline towards sanctions relief.
According to IRNA, 139 lawmakers out of the 253 present voted in favour of the bill, which looks to have overcome strong opposition from hardliners in Irans parliament.