Assuming you are age 50 or older, you do not have an excess salary deferral. This is because the 457(b) Plan has its own separate limit.
The maximum Deferral to your 401(k) Plan is $18,000 if you are under the age of 50 or $24,000 if you are age 50 or older. This limit is not affected by your contributions to your 457(b) Plan.
The maximum Deferral to a 457(b) Plan (Including Employer Contributions) is $18,000 if you are under the age of 50 or $24,000 if you are age 50 or older. This limit is not affected by your contributions to your 401(k) Plan.
For additional information, click this IRS link:
How-much-salary-can-you-defer-if-youre-eligible-for-more-than-one-retirement-plan.