If I decided to take a 401k loan (from a traditional 401k), I pay the loan back to myself with interest in after-tax dollars. When I take distributions on these funds in retirement, do I pay tax again on this money?
Assuming that you do not default on the loan and cause it to become a deemed distribution, only the interest paid to the 401(k) on the loan is paid with after-tax dollars. The loan principle is paid back with the before-tax dollars you were originally loaned.
The interest paid to the 401(k) on the loan does not become after-tax basis in the 401(k). You'll pay taxes again on this money when distributed.
If you default on the loan and cause it to become a deemed distribution, which is taxable, the deemed distribution does not satisfy the loan. You'll still be required to pay back the loan but any amounts that you later pay on the loan that are attributable to the deemed-distribution amount become after-tax basis in the 401(k) that will be tax-free when eventually distributed.
the plan must permit loans (otherwise it's a distribution). It must be paid back in 5 years otherwise a deemed distribution. There are limits on the amount that can be loaned. you must pay interest on it. the interest is not tax deductible unless used to buy a principal residence. The plan receives no basis for the interest paid, so it's taxable as part of the distributions you'll take just like if the money was earned form the plans other investments.
Okay, walk me through this scenario. Let's say I take out a $30,000 401k loan at 6.5% interest. I set up a repayment period of 36 months. After 25 months, I separate from my company - and at that time owe approximately $10k. A few months after separating from my company, but before filing my tax return for that tax year - I pay the loan back in full. Now since I paid the post-separation balance of $10k with money that I already paid taxes on, would I get to take that $10k as a deduction on that years tax return? Or, would my 401k account now have some money that is post-tax mixed with money that is pre-tax? If the latter, what would happen if I rolled that 401k into an IRA?
chagrinboy, in your example (where the loan never becomes a deemed distribution) the $10,000 that you are using to pay off the balance of the loan is $10,000 of the pre-tax money you received as the loan, not after-tax money.
If an offset distribution is used to pay off the $10,000, it's effectively a taxable distribution from the 401(k) that is used to replace $10,000 of the pre-tax loan that you spent on something else, which is pre-tax money that is turned around to repay the loan. If you can come up with the $10,000 from some other source to do so you have until the due date of your tax return plus extensions to roll the offset distribution over to an IRA to continue to defer the taxes.
In the case where you default on the loan but do not separate from service, the outstanding loan balance becomes a taxable "deemed distribution" but the loan is not satisfied. Subsequent repayments of the loan principal (but not the interest) then do become after-tax basis in the plan and that after-tax basis becomes basis in nondeductible traditional IRA contributions if the plan balance is later rolled over to a traditional IRA.