Citing sources close to the Swiss government, Swiss paper Tages Anzeiger and the German Süddeutsche Zeitung said that in January 2017 the two countries concluded a ‘Memorandum of Understanding' to forbid each country's intelligence service from carrying out espionage activities against the other.
From now on, Switzerland will tell the German government if it wishes to conduct an anti-crime operation in Germany, and vice-versa.
Contacted by the papers, neither government would confirm the existence of the agreement.
The news comes two weeks after German prosecutors arrested a Swiss man identified as Daniel M. in Frankfurt for carrying out alleged espionage activities since 2012.
The man's mission was to identify German tax investigators who purchased CDs containing details of bank account holders in foreign tax havens such as Switzerland.
The information provided helped Swiss authorities file charges against three German tax inspectors for breaching Swiss banking laws and economic espionage.
His espionage activities took place before the negotiations for the anti-spying agreement.
Swiss MP Corina Eichenberger, vice-president of a delegation that supervises the FIS, said such counter-espionage was part of the intelligence service's remit and that this operation was carried out within the law.
The issue of the ‘tax cheat' CDs has upset Swiss-German relations in the past.
Since 2006 German states have paid millions to unknown sources for the CDs, resulting in a major crackdown on tax cheats.
Many of Germany's rich and powerful have had to issue public apologies for stashing away their wealth abroad, while many others have been compelled to come forward and report their accounts abroad, pay back taxes on the interest earned plus a fine.
However things have changed considerably since then and such ‘tax cheat' CDs are no longer necessary.
In 2015 Switzerland made efforts to end banking secrecy by agreeing to the automatic exchange of information on bank accounts held by foreigners in Switzerland.