Otherwise excludable when YOS is elapsed time?

What happens when the plan's method of crediting hours of service is the elapsed time method?

is a Year of Service merely when someone works for 12 months straight (or credited due to spanning rules)?

How does that translate to calculating Otherwise Excludable?

I have a participant in q 403(b) plan who was hired 7/3/18 and worked 350, 650, 675, 720 hours in '18, '19, '20 and '21.

Is the OEX rule purely 1,000 hours in a year, or can it be based on elapsed time and depends on the plan's definition?

can this person be OEX or no?

Here's a clip from 1.410(b)-7:

(3) Plans benefiting otherwise excludable employees. If an employer applies section 410(b) separately to the portion of a plan that benefits only employees who satisfy age and service conditions under the plan that are lower than the greatest minimum age and service conditions permissible under section 410(a), the plan is treated as comprising separate plans, one benefiting the employees who have satisfied the lower minimum age and service conditions but not the greatest minimum age and service conditions permitted under section 410(a) and one benefiting employees who have satisfied the greatest minimum age and service conditions permitted under section 410(a). See § 410(b)-6(b)(3)(ii) for rules about testing otherwise excludable employees.

Since elapsed time doesn't require the 1000 hours, your plan doesn't use the greatest minimum age and service conditions permitted, and so I think you've got an excludable there.

It depends on the plan definition. If your plan uses elapsed time, use elapsed time service to determine 1 year of eligibility service (for the otherwise excludible employee rule). See 1.410(a)-7(c)(2) for how elapsed time works for determining a year of service with respect to eligibility to participate. (Those regs are ancient and were written when plans were allowed to use age 25 and 1-year of service, but the same principles still apply).   From your description it seems this person is probably not otherwise excludible, but you have to look at the service spanning rules to see if they have less than a year of service as of each of the entry dates during the plan year. (Otherwise excludibles for an elapsed time plan would be those who you let in with less than 1 year of elapsed time service, not those with more than a year of elapsed time service who you could have determined to have less than a year using a different method of counting service).