A case from the Northern District of California (Coble v. Bonita House, 789 F. Supp. 320) (1992) seems to suggest that if the employer changes coverage AFTER the COBRA recipient relocates, the employer must provide comparable coverage even if it does not provide coverage to employees or COBRA recipients outside their service are.
Based on the SPD, she should be able to defer 15% of pay PLUS $6,000 in catch-up deferrals, the $18,000 limit is irrelevant to her since 15% of pay is less than $18,000. Not allowing is an operational defect for the plan.
There is also a universal availability requirement for catch-ups [1.414(v)-1(e)]. If they are going to allow catch-ups, all catch-up participants must have the effective opportunity to make the same dollar amount of catch-up contributions.
I'm not particularly worried about the timing. There's nothing inherently wrong with making a deposit early. But you just have to pass all the tests at the end of the year and that's why we recommend not doing so. As of now, I still think it's a compensation issue. If it turns out there's not enough comp to support the deposit, then the document will explain what to do with a 415 excess contribution.