Maxing out a 401(k) is beneficial if you have an emergency fund, no high-interest debt, adequate insurance, and no imminent large expenses. If the employer's plan has high fees or poor options, consider an IRA first. Maximizing a traditional 401(k) offers significant tax savings. After maxing 401(k) and IRA, consider HSAs and other tax-advantaged accounts. The main downside is reduced current cash flow, especially for younger workers.