When is a CFII required to provide instrument training? 61.195(c) states: 


  (c)Instrument rating. A flight instructor may conduct instrument
  training for the issuance of an instrument rating, a type rating not
  limited to VFR, or the instrument training required for commercial
  pilot and airline transport pilot certificates if the following
  requirements are met:
  
  (1) Except as provided in paragraph (c)(2) of this section, the flight
  instructor must hold an instrument rating appropriate to the aircraft
  used for the instrument training on his or her flight instructor
  certificate, [...]


So as a CFI with a current instrument rating (but not yet a CFII) it appears I can provide instrument training to students working toward their Instrument Rating. I'm trying to find what limitations to this there are - what regs state when training must be from a CFII?

61.65 - Instrument rating requirements (d)(2) states:


  (2) Forty hours of actual or simulated instrument time in the areas of
  operation listed in paragraph (c) of this section, of which 15 hours
  must have been received from an authorized instructor who holds an
  instrument-airplane rating, [...]


Throughout 61.65 it consistently states only "authorized instructor" but there is no definition for "authorized instructor" except only as in 61.1(b) which reads: 


  Authorized instructor means— (i) A person who holds a ground
  instructor certificate issued under part 61 of this chapter and is in
  compliance with §61.217, when conducting ground training in accordance
  with the privileges and limitations of his or her ground instructor
  certificate; (ii) A person who holds a flight instructor certificate
  issued under part 61 of this chapter and is in compliance with
  §61.197, when conducting ground training or flight training in
  accordance with the privileges and limitations of his or her flight
  instructor certificate; or [...]


61.197 is only Renewal requirements for flight instructor certification.
So by all this, it seems to me that as a CFI with an instrument rating I'm authorized to provide instrument training. There's definitely something missing here and after hours of digging through regs I just can't find any clearer definitions on this. Can anyone help provide some guidance on where it's defined as to when a CFII is required? Thanks in advance.
No, you cannot provide


  instrument training for the issuance of an instrument rating, a type rating not limited to VFR, or the instrument training required for commercial pilot and airline transport pilot certificates


Unless you hold


  (1) Except as provided in paragraph (c)(2) of this section, the flight instructor must hold an instrument rating appropriate to the aircraft used for the instrument training on his or her flight instructor certificate,


Having an instrument rating on your CFI makes you a CFII.

You are confusing a CFII, who is a CFI with an instrument rating on his / her flight instructor certificate, with

someone that has an instrument rating on his / her pilot certificate and who also might hold their CFI.

You must be a CFII to give instrument training, the exception to that would be for private pilot candidates from 61.109


  (3) 3 hours of flight training in a single-engine airplane on the control and maneuvering of an airplane solely by reference to instruments, including straight and level flight, constant airspeed climbs and descents, turns to a heading, recovery from unusual flight attitudes, radio communications, and the use of navigation systems/facilities and radar services appropriate to instrument flight;


a CFI is able to give those 3 hours of instruction.  Anything beyond private pilot is the realm of the CFII.