The reason people have a 401K retirement plan is so they can fund their older years when they don't have an income. Many financial planners advise against taking out 401K loans, because it means that you are taking away some of your secure retirement funds.
You can always withdraw funds from your 401K account, but the 401k rule and tax penalties make this a very costly action. If you are considering taking out a 401K loan, make sure it is for an excellent reason and only as a last resort. There are no government rules about the loans but many employers do set restrictions, such as keeping a minimum balance, how may loans you can have at once, and that married employees must get consent from their spouse.
It is the plan administrator who will impose the most conditions on your 401K loans. Most administrators require that you have a valid reason for applying for the loan, and generally will only approve it if it is for one of the following reasons: medical expenses, college tuition fees, deposit for first home buyers, to prevent bankruptcy or eviction because of falling behind with mortgage payments. A 410K loan should not be for day to day expenses.
The good parts of 410K loans are how easy they are to apply for; any interest you pay goes back into your account; interest rates are competitive, even for those who have a bad credit rating; they are risk-free because you are actually borrowing your own money.
The bad parts of 410K loans include some 401k rule limitations on new contributions while the loan is outstanding which affects any employer contributions you may have been receiving; the interest you pay is not tax deductible; there is a relatively short term of the loan compared to other types of loans.
There are several alternatives to a 410K loan available which may be a preferable way to go for these major expenses, which might be worth investigating before you apply. Consider both the good and bad aspects of 410K loans carefully, before you apply.