You're tax return will simply show it as a "ROLLOVER." TurboTax will not prompt you to enter any explanation statement, so you would need to prepare that separately and include it with your mailed tax return. It's relatively common for the IRS to question an ordinary indirect rollover to a 401(k), so it seems even more likely that, without an explanation, the IRS would question a rollover to a 401(k) of an offset distribution given that no cash is actually distributed in an offset distribution.
