Plan effective 10/1 and deferral/ SH Match limits

If a client plan starts 10/1 - are they able to defer the max 19,500 as long as they have adequate compensation?  Is the safe harbor  basic match -the full 4% or is it pro-rated?  Thanks!

402(g) is a calendar limit.

Ok so as long as they don't exceed 19500 in that year  they are good?

Do you have a short plan year from 10/1 to 12/31 or do you have an effective date of 1/1 to 12/31 with the 401(k) componenet effective 10/1?

In the first case you would prortate your 415(c) and 401(a)(17) limits, in the second there would be no proration.

short plan year beginning 10/1

Then it gets prorated.  Not the 19,500, but the 415 and comp limits

Then if you are talking about 2021 for a 3 month plan year -

415(c) is 58,000 x 25% = 14,500

401(a)(17) is 290,000 x 25% = 72,500

Max match in your example is 4% of 72,500 = 2,900.

With the $6,500 catch-up your maximum allocation for the short year would be $21,000.

So if they are getting the full $2,900 match (and no other employer contribution) they could defer up to 18,100 without exceeding the 415(c) limit.