两份加起来不超过上限, 18000不包括雇主的contribution

www.irs.gov/Retirement-Plans/How-Much-Salary-Can-You-Defer-if-You%E2%80%99re-Eligible-for-More-than-One-Retirement-Plan%3F

How Much Salary Can You Defer if You’re Eligible for More than One Retirement Plan?

The amount of salary deferrals you can contribute to retirement plans is your individual limit each calendar year no matter how many plans you're in. This limit must be aggregated for these plan types:

• 401(k)
• 403(b)
• SIMPLE plans (SIMPLE IRA and SIMPLE 401(k) plans)
• SARSEP