On October 13, 2015 the Iranian Majlis approved, by a majority of 161-59 with 13 abstentions, not the JCPOA but rather an Iranian amended version it.
Paragraph 3 of the Majlis decision states that "the government will monitor any non-performance by the other party [to the agreement] in the matter of failing to lift the sanctions, or restoring the canceled sanctions, or imposing sanctions for any another reason, and will take steps to actualize the rights of the Iranian nation and to terminate the voluntary cooperation [this apparently refers to the Additional Protocol, which, according to the JCPOA, Iran will implement voluntarily] and to handle the rapid expansion of the Iranian nuclear program for peaceful purposes, so that within two years the enrichment potential in Iran will reach 190,000 SWU. The Supreme National Security Council will handle this matter, and the government will to submit to the Council a plan in the matter within four months."
Given that the non-cancellation of the sanctions is part of the JCPOA (according to the JCPOA, U.S. sanctions will be merely "suspended," rather than canceled, so as to allow their "snapback" in the case of an Iranian violation); and given that the re-imposition of sanctions, and the imposition of new sanctions, in case of an Iranian violation are likewise part of the JCPOA, it follows that the Majlis decision constitutes ratification of a nonexistent document. It was not a ratification of the JCPOA as it stands, but rather of additional demands made by Iran after the JCPOA was agreed upon on July 14, 2015 in Vienna.
Furthermore, the inclusion of these new Iranian demands in a Majlis decision constitutes the first written demand by an Iranian authority to amend the agreement, a demand that was mentioned verbally on September 3, 2015 by Iran's Supreme Leader Ali Khamenei.
The Majlis decision defines clauses in the JCPOA as "non-performance of the agreement by the other party" and therefore the Majlis' approval is meaningless.
 ISNA (Iran), October 13, 2015.
 Khamenei announced explicitly on September 3, 2015 that he does not accept the terms of the agreement and demanded that the sanctions should be immediately removed, rather than suspended, as a condition for accepting the agreement. See the following MEMRI reports:
Special Dispatch No. 6151, "Khamenei Declares That He Will Not Honor The Agreement If Sanctions Are Merely Suspended And Not Lifted," September 4, 2015; Special Dispatch No. 6162, "Expected September 28 NY Meeting Between P5+1 Foreign Ministers And Iran Could Signify Reopening Of Nuclear Negotiations To Address Khamenei's September 3 Threat That If Sanctions Are Not Lifted, But Merely Suspended, There Will Be No Agreement," September 21, 2015.