I seriously doubt we will ever know the true budget....there is very little sunlight when it comes to this type of things....obviously by design.
This article is dated 5/2016, so it seems the military budget was actually increased overall for the 1st and second year in office. The reallocation of the money around may have been used to falsely claim the Rouhani govt slashed funding.
"After the Management and Planning Organization released
official budget documents for the current Iranian year in mid-March, shock spread through right-wing media outlets and publications. Many of them lashed out at Rouhani under headlines such as “The administration has
decreased the defense budget.” Despite such assertions, was there actually a proposed decrease in the defense budget?
https://www.al-monitor.com/pulse/or...ending-irgc-budget-reduced-army-increase.html
Based on the number of personnel employed by the
Armed Forces of the Islamic Republic of Iran, the army has the most troops, weapons and military installations at its disposal. The Islamic Revolutionary Guard Corps (IRGC), possessing about one-third of Iran’s military power, is ranked second. Following them are the paramilitary Basij organization, the Ministry of Defense and the Armed Forces General Staff. Although the army's capabilities far exceed those of the IRGC, the latter always receives almost two times as much funding as the former.
In the fiscal year that began March 20, 2013, the first five months of which took place during President Mahmoud Ahmadinejad’s last year in office, Iran’s
total defense budget was $6.24 billion. In the following fiscal year, beginning March 21, 2014, marking Rouhani’s first full year in office, the defense budget grew by $1.85 billion, bringing the total to more than $8 billion.
This is from a (Dec 2018) 2019 article about the current budget:
https://en.radiofarda.com/a/iran-defense-ministry-budget-declines-irgc-more-funding/29679511.html
"Not many details about Iran's budget bill for the next year, presented to the parliament on December 25, have been publicly released.
However, a few key points about Iran's defense budget for the next year were leaked the day after President Hassan Rouhani presented the bill amid heckling and protests by a group of hard-line MPs.
Many Iranians on social media, mainly regime supporters, protested against what they called "a dramatic decline" in Iran's military budget.
Iran's defense budget covers spending for the army, the IRGC, the Basij, the Defense Ministry, and the Joint Staff of the Armed Forces.
In a series of tweets on December 25, Hossein Dalirian, editor of the IRGC-linked Tasnim news agency's defense desk, presented details about next year's defense budget that while indicating a decline in the budget of the Iranian Army,
the budget allocated to the Islamic Revolutionary Guards Corps (IRGC) has increased.
Dalirian wrote that Iran's total annual defense budget for the next year has been deceased by 27.3 percent while the budget for the Defense Ministry, which manufactures hardware such as missiles, has been decreased by 50 percent.
The IRGC's overall budget was
increased from 202 trillion to 255 trillion rials or $4.7 billion.
Iran's official budget numbers should be taken with a grain of salt, especially when it comes to military and intelligence activities. Given lack of overall transparency, money from various sources can be funneled to clandestine activities.
In January 2018, the Rouhani administration withdrew some $4.8 billion from the National Development Fund to amend the budget allocated to the IRGC and state-controlled broadcaster IRIB.
It could well be that reductions in some military budget line items in the current bill can be later increased with money withdrawn from the special development fund, which is supposed to help ensure the well-being of future generations.