How to close 2020 fiscal year on june30,2021. this fiscal year will be 18 months.

Hello there, @md41.

In QuickBooks Online, you can close the fiscal year in the settings. Before closing it, make sure you have reconciled your accounts up to your closing date and review your inventory quantities. 

Then, you can proceed following with these steps to close the fiscal year:

1. Go to the Gear icon.
2. Select Account and Settings.
3. In the Advanced tab, select Edit in the Accounting section.
4. Select the Close the books checkbox.
5. Enter a closing date. You shouldn't need to edit any transactions before this date. 
6. Select the Allow changes after viewing a warning and entering a password option from the drop-down menu if you want to require a password before editing your closed books. 
7. To change the first month of the fiscal year, click the drop-down arrow and change it to the appropriate month.
8. Click Save. Then, Done.
   

To help you more in completing certain tasks in QuickBooks Online to prepare for the new year, you can visit and get more details from this article: QuickBooks Online year-end guide and checklist. You can also use the Exceptions to Closing Date report to see any changes made after you close your books. Here's how:

1. Go to the Reports tab.
2. In the search field, enter Exceptions to Closing Date and open the report.
3. Customise or memorise the report if you want.

Please comment below if you need more assistance. I'm always around to help you more. Take care and have a good one, md41.