The new federal law on nationality is among a number of legal revisions to come into effect with the new year.
In future only those immigrants who have a C residence permit will be eligible to apply.
Stricter language requirements will also come into effect: candidates will have to demonstrate their ability in a Swiss national language in a written test.
Until now there has been no consistency in language testing, with many cantons in the French-language region making a judgment based on the candidate's oral skills.
“Candidates' linguistic abilities were evaluated at an interview with the commune or cantonal naturalization committee,” said Christophe Maillard, head of the canton of Fribourg naturalization service in comments quoted by Le Matin.
The new law formalizes the language requirement, with candidates having to demonstrate A2 level writing ability and B1 spoken skills under the Common European Framework of Reference for Languages.
The cantons can raise the bar even higher if they wish. The Thurgau cantonal government decided in November that its applicants for citizenship must have B2 level speaking ability.
The language tests will take place in accredited language schools, Le Matin said, and cost the applicant a maximum of 250 francs.
Candidates whose mother tongue is a Swiss national language or who have studied for at least five years in one of these languages will not be required to undergo the test.
Another change affects social welfare. Until now applicants in receipt of welfare benefits were excluded from applying for citizenship.
From January this will be extended to include those in receipt of social welfare in the three years prior to their application.
An exception is made if the benefits are paid back in full.
In one important respect the application process is being eased, with candidates only having to have been resident in Switzerland for 10 years instead of the current 12.