Does the Mass Copy process copy assets to the tax book if the corporate book period is closed?

You can run the Perform Periodic Mass Copy process for both open and closed corporate periods.

When you submit the process, you must select the corporate period the process should be run for. The period you select can be either the current open period or a closed period. If you use monthly periods for both the corporate and tax books, the current open period in the tax book must be the same period selected for the Perform Periodic Mass Copy process. If you use monthly periods in the corporate book and yearly periods in the tax book, you must ensure that the corporate period falls within the fiscal year of the tax book.

Note that once you successfully run the Perform Periodic Mass Copy process for a period, the list of values for the Period parameter displays the period the process was last successfully run for and the next period.