It seems like you can repay even after you paid taxes on the first third. But the way I read the rules, that part a bit vague.
So lets say you took the whole $100,000. If you paid tax on $33,333 last year, you could repay 1/3 as a rollover/repayment to ANY rollover IRA or 401(k) (not the one it came out of necessarily) this year and not pay any tax this year. It is coded as a rollover on the Form 5498.
Then next year you could repay or pay the taxes. Very flexible. But make sure first by doing research, don't take my word for it.
