Are Employee paid health insurance premiums for employees on long term disability (LTD) considered imputed income in 2015?

I receive Long Term Disability benefits through my company for many years now, and one of those benefits is that they directly pay my health insurance premiums. I do not pay any premiums. Employees on regular wages have their health insurance premium deducted from their paychecks. This year is the first time that I received a letter from my employer that states that starting calendar year 2015, their contribution to my health plan is considered imputed income and that I will have to pay income taxes on it. Please advise. My health insurance policy is the same one that is offered to every other employee in the company who is on regular wages. The only difference being is that the employees who are on regular wages have their premiums deducted from their paycheck every pay period and employees who are on Long Term Disability (LTD) have those exact same health insurance premiums paid for by the company. The company's LTD policy includes their payment of the health insurance premiums for the employees on LTD who are also on the company offered health insurance plans. These are the same plans offered to all employees. In addition, the health insurance policies offered by the company are "self-funded" by the company and administered by various health insurance companies. Does this information still equate with the company paid LTD employee health insurance premiums suddenly being considered in 2015 as imputed income? I've spoken to my company's Benefits Department and the IRS, and reviewed their websites. My Benefits department cannot state what IRS or tax law they are basing their decision to consider company paid health insurance premiums for LTD participants as imputed income. I also spoke to the IRS and their ACA specialists, and they can't find any language that states that company paid health insurance premiums for LTD participants is considered imputed income. I'm not sure where or who to turn to find the real answer with the actual IRS, ACA , federal or tax law language to back it up. How do I find out the reason for the change? or the reference in tax law that would make this benefit taxable? I know my status with the company is as an "employee on leave" on "long term disability". Under IRS 2015 Publication 15-B, Section 2, page 5, it discusses discusses the exclusion rules that apply to fringe benefits and this includes accident and health benefits. I'm confused as to how the employer paid health insurance premiums are considered income when the IRS Publication considers it an excludable benefit not subject to federal in-come tax withholding. Do you have a link to or the name of the IRS, ACA, federal or tax law where it defines employer paid health insurance premiums for employees on Long Term Disability as taxable income? Please advise.