Hey guys,
I work with 401K plans so I'll try to clear up a few things.
Every plan is different, whether you can take out a loan at all (some plans don't allow them) or what type of loans you can take (general purpose, primary residence, hardship) is determined by your company when they setup the plan.
The time you can take to pay yourself back is also set by your company, typically general purpose loans have a max payback time of 5 years.
Some plans require paperwork like a credit agreement and spousal consent form (sometimes this is required even if not married).
The rate of interest is also set, a common one is either prime, prime +1, or prime + 2%.
**Important note about the interest** While it's true you are paying the interest back to yourself, it's important to note that you are double taxed on the interest. When you contribute money into your account pre-tax, obviously you don't pay taxes on the funds. When you pay yourself back from your paycheck, the payback is with after tax dollars. This is a wash regarding the principal portion of the payback because when you request a loan, they give you a net check. However, the interest is paid back to your account after tax, but is not treated that way once it is put back in. Therefore, when you finally withdraw your money, the interest dollars (which have already been taxed) will be taxed again at your current fed and state levels.
Another important item you need to check is to see what types of fees, if any, the plan charges. Many don't have any at all, but some have not only an origination fee (I've seen these as high as $100) and maintenance fees, typical amounts are $10 or $15 per year, charged proportionally every calender quarter.
Some have mentioned before, the most you can ever borrow from you account is $50K, though some companies set lower limits. You can only borrow from vested dollars, and some companies also restrict the sources of money you can borrow from. For example, some companies don't let you borrow from company match sourced dollars.
One last thing that was also already touched upon, if you leave the company and don't pay it back within a certain period of time, usually 90 days (some plans allow manually payments for former employees) or if you stop receiving a paycheck (out on disability) the loan may deem distribute (default) and you'll have to pay income taxes on the oustanding principal plus accrued interest from the last loan payment. In addition, if you are under 59 years and 6 months, you'll have to pay an additional 10% penalty. Depending on the size of the loan, keep in mind it can put you in a higher tax bracket.
Hope this helps.
