JR Commuter Pass question

My home station is Uguisudani, I take the Yamanote Line . I have a monthly pass that goes from Uguisudani to my workplace in Shinjuku.

Recently I've started going to Shimbashi for work as well, I go there about 3 times a week. But my I have to pay outside of my monthly pass as Shimbashi is on the other side of the Yamanote Line.

My question is, can I get a pass that goes from Shimbashi to Shinjuku even though I enter from Uguisudani everyday?

How about you try to buy one and find out?

(Yes.)

However, when you buy your commuter pass from Uguisudani to Shimbashi, you will need to buy a pass for the long way (which includes Shinjuku), not the short one.

Sorry, I misread. Yes, a commuter pass between Shinjuku and Shimbashi will also work, but here also you have to buy a pass for the longer way, which includes Uguisudani.

Basically, a commuter pass is a "free pass" like the JR Pass and other similar ones, but which is restricted to a particular route between two stations. As long as you travel on the covered route, you can travel freely.

Oh! this is "Living" Q but anyway,
No! commuter pass(定期券/teiki-ken) validity for "one fixed route" only
not valid for other route as detour or short-cut.

If buy new pass include "Uguisudani" you must specify fixed route (open rail map first)
https://upload.wikimedia.org/wikipedia/commons/c/c3/TokyoYamanoteAreaL...
[1] "Uguisudani - (via Ueno,Akihabara,Tokyo,Shimbashi,Shinagawa,Shibuya) - Shinjuku" 10020Y
means not valid for btw Uguisudani and Shinjuku closest route of Yamanote line also * route.
or [2] "Uguisudani -(via Ikebukuro,Shinjuku,Shibuya,Shinagawa by Yamanote line)- Shimbashi" 12280Y
means not valid for btw Uguisudani and Shimbashi closest route.
or [3] "Shinjuku -(via Ikebukuro,Uguisudani,Ueno,Akihabara,Tokyo) - Shimbashi" 7750Y
means not valid for closest * and via Shibuya,Shinagawa by Yamanote line route.
or [4] "Uguisudani -(via Ikebukuro,Shinjuku,*,Akihabara or Kanda,Tokyo)- Shimbashi" 10020Y
means not valid for Shibuya,Shinagawa by Yamanote line route but no problem as total(mentioned later)
*) via Sobu/Chuo line via Akihabara/Kanda as "short-cut" route (need one transfer)

But if no need new one as nclude "Uguisudani"
buy real paper ticket set "(普通)回数券/(fu-tuu)kai-suu-ken" better.
回数券 is a bit larger thin blue color based one like this
http://gorosetsuyaku.com/wp-content/uploads/2015/07/IMG_55571-700x525....
"Uguisudani - Simbashi[X]"
or "Shinjuku - Simbashi[Y]"
or "Uguisudani - Kanda[Z]" as new pass [4] via Chuo line

回数券 is oneway(no fixed direction) 11 tickets set but 10 tickets fare as discount.
(X/Y/Z : 2000Y/1700Y/1600Y, Validity period : 3 month)
Also 回数券 is NOT commuter pass so you can take any route via *(mentioned above)
but cannot stop over/途中下車/ticket gate out and return like bellow.
(A→B→C→[back]→B→[return]→C)
Purchasing 回数券 is easy by 指定席券売機(MV/Multiple Vender/thin purple colored frame one).
http://pds.exblog.jp/pds/1/200511/28/03/c0034203_22224472.jpg
No need paper work at ticket counter.
Also you can buy at 金券(kin-ken)ショップ/(discount)ticket shop near major stations.
https://www.google.co.jp/search?q=%E9%87%91%E5%88%B8%E3%82%B7%E3%83%A7...
But 金券ショップ is not Railway company stocks are not flat.

OR,
Buy "山手線内均一定期券/Yamatesen-nai-kinitu-teikiken(= flat rate commuter pass)".
This special PASS is super rare one as exception "one month" type only 14220Y
coverd Yamanote line(both loop) all also include Chuo line stns all btw Shinjuku and Tokyo
as unlimted ride like regular commuter pass.
This pass is best match but maybe not cheapest if not so many times.

Calc again and Ask at JR station ticket office
also your company's transportation fee adjustment section both.