RMD - plan year change

Current plan year end is 9/30/19. RMD is taken for 2019 based on 9/30/18 balance - 1.401a9-5-Q&A3

Amending the plan year to a short year from 10/1/19 to 12/31/19.

As a calendar 2019 RMD is already taken, will there a need for further allocation requirement based on 9/30/19 balance?

If there is, what is the methodology?

Thank you

RMDs are a calendar year requirement.  You correctly used the last valuation date in 2018, 9/30, for the 2019 calc.  The only effect of changing the FY is that for 2020, you will have a 12/31/2019 val date and therefore a 12/31 account balance to use in those calcs.