Spain allows dual citizenship with 25 countries

Spain allows conditional dual citizenship only with 25 treaty countries which have bilateral agreement permitting dual citizenship. The rules apply differently for spanish nationals born in Spain and foreigners who naturalize for citizenship. Exception is granted for Sephardic jews who apply for spanish nationality who can keep their existing nationality. Children with double citizenship, who are born outside of spain to spanish parents must declare to conserve their Spanish nationality between ages 18 and 21

• Dual citizenship is permitted for all Spaniards by origin, as long as they declare their will to retain Spanish nationality within 3 years of the acquisition of another nationality, else it is lost. This declaration is waived with treaty countries (listed below)
• Foreign nationals who acquire Spanish nationality must renounce their previous nationality, unless they are natural-born citizens of a treaty countries – Latin American, Andorra, the Philippines, Equatorial Guinea, or Portugal, France. (listed below)

Treaty countries

Below are the full list of treaty countries which have agreements on dual citizenship with Spain.

1.  Andorra
2. Argentina
3. Bolivia
4.  Brazil
5.  Chile
6.  Colombia
7.  Costa Rica
8.  Cuba
9.  Dominican Republic
10.   Equatorial Guinea
11.   Ecuador
12.  France (from Apr 1, 2022)
13.  Philippines
14.  Guatemala
15.  Honduras
16.  Mexico
17.  Nicaragua
18.   Panama
19.   Paraguay
20.   Peru
21.   Portugal
22.   Puerto Rico
23.   El Salvador
24.   Uruguay
25.   Venezuela

Spain does not have a dual citizenship treaty with United Sates and United Kingdom, so dual citizenship is still not permitted. For example US/UK citizen naturalizing for spanish citizenship must renounce their previous nationality. Likewise Spanish born citizens who become US citizens must declare to retain their spanish nationality within 3 years of becoming US citizen.