I am getting a Chapter 14-12C. Will I have to do time in the reserves?

You are going to the streets. No Reserves, no Guard. You are going to be advanced to PFC.......Private Friggin Civilian

No, you are not eligible to transfer into the reserves or the IRR. On your DD214 where it says "Component transferred to:" yours will say N/A.

Are you getting a dishonorable discharge?
If so, you will not be in the reserves and you will not even be in the IRR.

No. Your enlistment contract is 8 years. All initial enlistments are 8 years. You have that obligation whether the time is all AD, all Reserve or a combination. Typically a troop serves from 2-6 years as AD or reserve and the remainder as IRR unless they re-enlist.

Chapter 14-12c is a serious offense discharge. You likely will not have reserve obligations once that is processed but will have IRR until your contract termination.

Part of the chapter process should involve an ability to speak with an attorney. You should go to your local Trial Defense Services (TDS) office and ask them these questions. It they cannot help, politely ask who can. Your retention NCO should be able to answer or point you in the right direction too. TDS is probably your best starting point.

You made your own bed, now you get to lay in it; should have thought about this stuff beforehand.

Brutally honest, If you are being kicked out as a 2 time drug offender, chances of you getting into the reserves are slim and none.

It depends on the character of your discharge. Honorable or General you will have IRR. Other than Honorable or Dishonorable no IRR.

Whether you can volunteer for Guard or Reserve will depend on you reenlistment codes.

AR 635-200, para 1-35
1–35. Eligibility/ineligibility for transfer to the IRR a. Soldiers with a remaining MSO may be transferred to the IRR upon release from active duty if they meet all of the following criteria: (1) Have completed initial entry training (IET) and have been awarded a military occupational specialty (MOS). (2) Have three or more months remaining on their MSO. (3) Are assigned a characterization of service of honorable, or under honorable conditions (general), or have service described as uncharacterized if in entry-level status. (4) Are determined by the separation authority to possess the potential for useful service if ordered to active duty under conditions of full mobilization. b. Soldiers with a remaining MSO are ineligible for transfer to the IRR and will be discharged if they meet any of the following criteria: (1) Have not completed IET and have not been awarded a military occupational specialty (MOS). (2) Have less than three months remaining on their MSO. (3) Are separated with a punitive discharge (bad conduct or dishonorable) as a result of a court-martial (4) Are administratively separated with a service characterization of under other than honorable conditions (5) Are released from the custody and control of the Army by reason of void enlistment. (6) Are separated for physical disability under AR 635–40. (7) Are administratively separated voluntarily for any of the following reasons: (a) Sole surviving sons or daughters. (See chap 5.) (b) Medical failure for flight training. (See chap 5.) (c) Hardship, dependency, parenthood. (See chap 6.) (d) In lieu of trial by court-martial. (See chap 10.) (e) Entrance into officer accession programs. (See chap 16.) (f) Conscientious objection. (See AR 600–43.) (8) Are administratively separated involuntarily for any of the following reasons: (a) Parenthood. (See chap 5.) (b) Lack of jurisdiction. (See chap 5.) (c) Illegal alien. (See chap 5.) (d) Concealment of arrest record. (See chap 5.) (e) Minority. (See chap 7.) (f) Fraudulent entry. (See chap 7.) (g) Alcohol or drug abuse rehabilitation failure. (See chap 9.) (h) Unsatisfactory performance. (See chap 13.) (i) Misconduct. (See chap 14.) (j) Rescinded. (k) Military personnel security program. (See AR 380–67.)