Can i lock a period after the BAS is complete

Hi kaylene-prestonc,

Thank you for posting in the Community! Yes, you can lock a period after you complete your BAS. Lodging your BAS will be considered as lock on that specific period. To lodge a BAS, you can follow these steps. 

1. Go to GST tab. 
2. Select Prepare BAS. 
3. Review the amounts on each tax you've enabled on your tax settings.
4. After reviewing the complete activity statement, select Mark as lodged to close the tax period in QuickBooks.

For your reference, you can check on these articles: 

How to lodge a BAS or IAS in QuickBooks Online

Close your books in QuickBooks Online

Feel free to drop a comment below if you need any help with your BAS. Have a great day!