Don't be afraid of Father Time. D365 Year End Close.
The short and sweet Year End Close creates beginning balances for the new year's Trial Balance. There is no need to be afraid of the process. You will probably do it several times while you are finishing up your December journals.
1. Setup the Fiscal Year Close Parameters
General ledger > Setup > General ledger parameters > Ledger > Fiscal year close (fast tab)
Setup as exhibited.
2. Setup the Retained Earnings posting profile
General ledger > Setup > Posting setup > Accounts for automatic transactions
Create a new posting profile pointing the your Retained Earnings main account.
3. Run the Year End Close
General ledger > Periodic tasks > Period close > Year end close
1. Drop down "Run fiscal close".
2. Select all legal entities by checking the top left check box.
3, Click "OK".
Happy New Year !