From: Rabbi Moshe Sofer
To: Rabbi Ploni
The Chasam Sofer rules that a communal rabbi's salary is not a contractual wage subject to secular scala (currency-adjustment) laws, but rather an ongoing halachic obligation to provide full livelihood according to actual needs. When currency depreciation, rising prices, and family growth render the original stipend inadequate, the community must increase it accordingly. Pragmatically, he advises the Beis Din to use the scala laws themselves as leverage to extract maximum support for the rabbi.
Source: Shu"t Chasam Sofer CM §166