Can Apple use its off-shore cash to do Apple stock buy-backs tax free? It is well established that Apple holds $181B in cash overseas. This appears to be to avoid US Taxes. 

Apple has been doing significant stock buy-backs. 

My question is: Can Apple use its off-shore cash to do Apple stock buy-backs tax free?
To the best of my knowledge - and I'm not an accountant, so I may very well be wrong: buybacks are not profits, but are instead considered as an 'investment' in Apple in its own company. Since they are not profits, they are not taxed.

Apple using its offshore cash to buy back its own stock is changing the accounting balance rather than actually generating any profits.

Consider the following balance sheet:

        Assets  
Cash      100M 
   Liabilities
Loans      70M
        Equity
C. Stock   22M
R. Earnings 8M


In this balance sheet, the retained earnings (what is taxed) is 8M. 

With a buyback of 12M in common stock:

        Assets  
Cash       88M 
   Liabilities
Loans      70M
        Equity
C. Stock   10M
R. Earnings 8M


Retained earnings have not changed, the company's taxable income has not changed, and thus the company should not have to pay any taxes. 
This should be true regardless of where the money 'physically' is - in the U.S. or elsewhere.