Delay Until Fully Functional Act of 2013 - Amends the Patient Protection and Affordable Care Act to require the Comptroller General (GAO) to: (1) determine whether health care exchanges and all other point of enrollment options are fully functional and operating in a manner consistent with the role envisioned under the Act and report study results to Congress, and (2) conduct subsequent studies every 60 days until the Comptroller General determines that exchanges are fully functional and operating in such manner.

Delays the effective date of the penalty for failure to maintain minimum essential coverage to apply the requirements to taxable years beginning six months after the date on which the Inspector General of the Department of Health and Human Services (HHS) certifies to Congress the results of the GAO determination that exchanges are operating successfully.

Amends the Internal Revenue Code to exempt from the penalty an individual who is unable to enroll in a qualified health plan because of the technical or customer service issues of an exchange.