Subject: Re: BRK Overvalued Now?
"Not if the coupon-paying security is held in a non-taxable account such as an IRA or 401K, which is the logical place to hold coupon-paying securities. "

Unless you plan to someday retrieve any of the money. Then you pay tax at ordinary income rates for all of it - contributions, capital gains, interest, qualified dividends etc.

Those non-taxable accounts are just deferred tax accounts (Roth IRA is the notable exception, but you have to pay ordinary income tax to convert to the Roth - or contribute directly from taxed money)