The terms for issuance of a Schengen visa are listed in art. 23 of the Visa Code: 15 days, extendable in specific cases to 60.
The timeframe for issuance of national visas are set out in section 5 (8) of Presidential Decree 394 of 31.8.1999, as amended by D.P.R. 334/2004, which states that the diplomatic/consular mission, "after ascertaining that the application can be entertained, and after conducting the necessary investigations in relation to the visa, including the preventive security checks, shall issue the visa within 90 days of the date of application" (30 days for paid employment, 120 days for self-employment).
Pursuant to article 6(2) and (3) of Ministerial Decree 171 of 3 March 1997, these deadlines may be exceeded whenever it is necessary to carry out investigations or acquire information, documents and opinions from foreign authorities.
Any cases of forged documents produced by foreign nationals for the purposes of obtaining an entry visa shall always been reported to the Italian judicial authorities by the diplomatic or consular mission (article 331 of the code of criminal procedure). This applies both to the forgery of Italian documents and documents of foreign origin that are in any way used in support of a visa application (art. 3 par. 8bis of Legislative Decree 286/98).
In the event that the diplomatic/consular authorities are acquainted with any fact, situation or condition that would have prevented the grant of an entry visa that has already in granted, they must issue a formal REVOCATION measure.
The 21 types of entry visa
Inter-ministerial decree no. 850 of 11 May 2011 defines 21 types of entry visas, along with the requirements and conditions for obtaining them:
adoption, business, medical treatment, diplomatic, sports competition, invitation, independent work, subordinate work, mission, family reasons, religious reasons, re-entry, elective residence, research, study, airport transit, transit, transport, tourism, working holiday, volunteer work.