...In spanish,is there a rule as to when one may transition from using the polite "usted" to the familiar "tu"?....e.g. in the workplace when one first first starts working you may address a workmate as "usted" but when may that person be addressed as "tu'??

This sounds like a homework question...however school is out for the summer so I´ll give you the benefit of the doubt. :p

In general if someone is considered an equal in age or in rank they treat each other as tú. However, if you don’t know the person well (on a personal level) and they are your elder, or they have a higher rank than you, you would treat them as Usted.

So if you just started a new job and your workmate is about the same age and/or they aren’t your superior, you would treat them as "tú". In this case if you treated them as Usted they would find that really weird.

On a similar note, when I began my studies in Spain, I didn't know the vosotros form and when I first met my friends I treated them as Ustedes. They would joke and ask me who I was talking to because they weren’t old and they weren’t presidents. :hdspin:

...La Profa...i get what you are saying but maybe i didn't explain myself at all well. Taking your example in your second paragraph....initially i do not know my workmate (who is my elder) well but with time we get to know each other. Is there not a time, having got to know my elder workmate a lot better, and in a sense become friends,that i can use 'tu'. In english i would call my elder "Mr Smith" until such time that he tells me to address him as "Bob".

...another point...is the 'U' in Usted always written in the upper case?

...these are not homework questions...i promise...i wouldn't mind being that age again

The simplest manner to resolve your question of whether to address a person, after getting to know them somewhat, with the formal or informal, is to ask: ¿podemos tutearnos?

As to the U (or the V) in Usted...it is always in upper case...it is the shortened form of the medieval words..."Vuestra merced."

Sheryl

...Sheryl...thank you, that clears thing up for me.