Opposition politicians testily declined to follow suit, invoking Switzerland's tradition of financial secrecy that has long allowed citizens to keep details of their wealth under wraps even from the taxman without risking serious repercussions.
The decision by Jacqueline Fehr and Simonetta Sommaruga - both members of the center-left Social Democrats - to reveal their comparatively modest tax statements to the Sonntag weekly paper comes as the country struggles to embrace the kind of transparency long expected of politicians and officials in the United States and elsewhere.
Sommaruga, an enemy of Switzerland's powerful banks, went further, suggesting to Sonntag that lawmakers should automatically reveal how much money they receive from memberships on company boards and other business interests.
Such a move could be particularly hard for candidates such as Johann Schneider-Ammann of the pro-business Free Democrats, whose family is estimated by Bilanz magazine to be worth 500-600 million Swiss francs.
His fellow party member Karin Keller-Sutter told Sonntag that she favors keeping personal financial matters secret.
"I see no reason to disclose my tax information," she said.
The four, along with Jean-Francois Rime of the Swiss People's Party and Green Party candidate Brigit Wyss, are vying for two vacant seats in the cabinet. One belongs to outgoing Finance Minister Hans-Rudolf Merz, who brokered a deal with the United States last year that forced Switzerland to break its own banking secrecy laws in order to prevent the country's biggest bank, UBS AG, from facing damaging civil litigation in US courts for helping thousands of Americans hide money in offshore accounts.
Merz also caved in to demands by Washington, Paris and Berlin for greater assistance in future tax evasion investigations, a move that was widely seen as the beginning of the end of Switzerland's strict policy of noncooperation with foreign tax authorities.
The Swiss Parliament elects the new members of the cabinet on Sept. 22.
