Taking a loan from your 401(k) Borrowing against funds in your plan may be allowed. But is it ever a good idea? After years of regular contributions, a 401(k) plan through your employer may become one of your largest financial assets. In some cases, your employer may also allow you to borrow against the funds in that plan, which may be another financial benefit to you.As you continue to work and build for your retirement, you may be tempted to take a loan to cover emergencies or big expenses like college. But before you make that decision, there are some things you should know.You'll have to pay it backWith a 401(k) loan, you can generally borrow up to 50% of the vested balance in your 401(k) account, or $50,000 whichever is less. But a 401(k) loan has several drawbacks. First, the money has to be repaid, usually over a five-year period. If you quit, are laid off, or if the 401(k) plan is terminated, the loan will typically become due within 60 days. This could be a big financial strain on you in addition to setting back your retirement saving.Another drawback is that if the loan is not repaid when due, then the balance will be treated as a withdrawal, and may be subject to income tax as well as a 10% penalty tax if you are younger than 59 1/2 years old.You'll pay interest on the loanYou'll have to pay the money back with interest. The good news is, the interest is credited to your 401(k) account, not to your employer, so you are paying the money to yourself.Use for emergencies onlyIf you face a serious financial need, borrowing money from your 401(k) plan may make sense, as it can be easy to get. But consider it only after you've exhausted your cash savings accounts. Keep in mind if you leave your employer for any reason, a 401(k) loan can create a financial burden.