After the approval of the 17 Statutes of Autonomy, which took place between 1979 and 1983, almost all of them have been modified. In accordance with the provisions of article 147.3 of the Constitution, these reforms are carried out in accordance with the procedure established in each of them and require the subsequent approval of the General Courts, through Organic Law.

These modifications have taken place in successive phases and, at each moment, have had a different purpose and motivation.

They were intended to provide for the coincidence of the dates for the holding of elections with other Communities, as well as for the holding of local elections, so it only affected one article in each of the Statutes affected. It was formalized through these modifications:

• Asturias. Organic Law 3/1991, of March 13
• Cantabria. Organic Law 7/1991, of 13 March
• Murcia. Organic Law 1/1991, of 13 March
• Valencian Community. Organic Law 4/1991, of 13 March
• Castile-La Mancha. Organic Law 6/1991, of 13 March
• Extremadura. Organic Law 5/1991, of 13 March
• Madrid. Organic Law 2/1991, of 13 March

The modifications carried out during this period were more significant when they incorporated into the new texts the extension of the competence of the Communities constituted through Article 143 of the Constitution, especially in the field of health care and education. In the case of the C. Valenciana the reform meant incorporating the competences transferred by Organic Law 12/1982 (LOTRAVA). These amendments stemmed from the Autonomic Agreements signed on February 28, 1992 between the Government, the People’s Party and the Spanish Socialist Workers Party:

• Aragon. Organic Law 6/1994, of 24 March
• Asturias. Organic Law 1/1994, of 24 March
• Cantabria. Organic Law 2/1994, of 24 March
• La Rioja. Organic Law 3/1994, of 24 March
• Murcia. Organic Law 4/1994, of 24 March
• C. Valencian. Organic Law 5/1994, of 24 March
• Castile-La Mancha. Organic Law 7/1994, of 24 March
• Extremadura. Organic Law 8/1994, of 24 March
• Balearic Islands. Organic Law 9/1994, of 24 March
• Madrid. Organic Law 10/1994, of 24 March
• Castile and Leon. Organic Law 11/1994, of 24 March

The modifications carried out in this period had a greater meaning, both because of what they meant by the extension of competences and because of the institutional changes. In the case of the Canary Islands, it meant incorporating the competences transferred by Organic Law 11/1982 (LOTRACA).

• Asturias. Organic Law 1/1999, of 5 January
• Cantabria. Organic Law 11/1998, of 30 December
• La Rioja. Organic Law 2/1999, of 17 January
• Murcia. Organic Law 1/1998, of 15 June
• Aragon. Organic Law 5/1996, of 30 December
• Castile-La Mancha. Organic Law 3/1997, of 3 July
• Canaries. Organic Law 4/1996, of 30 December
• Navarre. Organic Law 1/2001, of 26 March
• Extremadura. Organic Law 12/1999, of 6 May
• Balearic Islands. Organic Law 3/1999, of 8 January
• Madrid. Organic Law /1998, of 7 July
• Castile and Leon. Organic Law 4/1999, of 8 January

The new system of financing of the Autonomous Communities and the transfer of taxes (mainly I. Personal Income, I. Added Value, I. Heritage, I. Successions and Donations, I. Patrimonial Transfers and Documented Legal Acts) forced a new process of reforms of the Statutes of the 15 Communities with common funding regime to adapt them to the provisions of Law 21/2001, of December 27. These modifications were limited to the paragraph affected by the new system of transfer of taxes, in each of the Additional Provisions of the Statutes. It was formalized by the successive Laws 17/2002 to 31/2002, of July 1, on the transfer of taxes from the State to each of the Autonomous Communities.

Since 2004 certain Autonomous Communities began processes of reform of their Statutes of Autonomy. In most cases its content is very relevant and involves the approval of new complete texts, with special attention and incidence in three areas:

• The expansion and greater competency precision
• The greatest relevance of the institutions
• The provision of instruments for participation and cooperation with the State

As it affected two Autonomous Communities constituted through Article 151, specifically Catalonia and Andalusia, the reforms of these two Communities required a referendum to approve the initial proposals of the respective Autonomous Parliaments and subsequently approved by the Cortes Generales.

Reform procedures on very specific and specific content are proposed and carried out.