F-2 for the wife, finance question

[kalhown]

Consider one is studying in a US university, Ph.D (full support guaranteed for the entire course of study).

After a year one decides to bring his official wife to US.

Many schools state that in order for them to issue I-20 for a spouse, student must document, e.g., "additional $12k for an academic year".

Questions:
1. Do people really have to accumulate these $12k during their first year?

2. What about future years? Do one and his wife must present these pesky $12k every year for prolongating "period of legal stay in US"?
This period I believe is D/S, or Duration of Study, for Ph.D. students since they are 100% supported by University.