From the IRS website about SIMPLE IRAs, “If an employee participates in any other employer plan during the year and has elective salary reductions under those plans, the total amount of the salary reduction contributions that an employee can make to all the plans he or she participates in is limited to $18,500 in 2022 ($18,000 in 2022 - 2017).”So, no you cannot contribute more than the original max of $18,500 total to an employer plan in a year. However, depending on income requirements, you might still be eligible to make $5,500 in contributions to a Roth or Traditional IRA, in addition to your 401k contributions. That could raise your potential tax-deferred savings to a total of $24k.