Final answer:
An annual salary increase is not a form of non-salary compensation for members of Congress as it affects their base salary. Other non-salary benefits include healthcare, retirement, and paid vacation, but salary increases take effect only in following sessions due to Amendment XXVII.
Step-by-step explanation:
All of the following are non-salary compensation for members of Congress EXCEPT for an annual salary increase. Members of Congress receive various forms of non-salary compensation such as healthcare benefits, retirement benefits, and paid vacation. However, an annual salary increase is not considered a non-salary benefit as it would directly affect their base salary. According to Amendment XXVII, members cannot raise their salaries during the current session of Congress, meaning any salary increases voted upon would only take effect in the next session, and are not received as part of their ongoing compensation package during a current term. This restriction was put into place to ensure accountability and prevent immediate self-dealing.
The non-salary compensation for members of Congress typically includes healthcare benefits, retirement benefits, and paid vacation. However, one form of non-salary compensation that they do not receive is an annual salary increase.