Cannot save transaction. Message: You cannot create on modify SST-Related transaction for this period

Scenario:

The user has already submitted the June SST return, but later discovered an invoice that was missed. When attempting to enter the transaction with a backdated date within the June period, the system prompts an error ‘The SST Return for 25/06/2025 has already been submitted. You cannot create on modify SST-Related transaction for this period’  

 This is due to the taxable period being locked after submission.

Solution:

1. Check the invoice date you want to create / modify. As the sample above, it is June 2025

2. Navigate to Tax > SST Return > Service (Click ‘Sales’ if your document is Sales Tax).  You’ll notice that the taxable period for June is already marked as "Submitted". Since this period has been submitted, all transactions involving SST tax codes for this period are locked and cannot be edited.

 3. There are 2 solutions for this scenario.  
1st solution: If user want to backdated key-in a transaction that already submitted SST on June, user can update Tax Date on the other taxable month that yet to submit SST.

Date: Document Date
Tax Date: SST Submission Date 

4. 2nd solution: If user really wants to include backed dated document on June within June taxable period, user can click ‘Unlock’ in SST Returns.

 Notice that there is Journal Entries been created since it already submitted 

Update the reason in the column then click ‘Unlock SST Return’ 

 5. System prompts reminder message that Journal Entries that created will be removed
 Click Yes to proceed  

The journal will be removed, and the status will revert to Draft.

At this stage, the user may re-enter the document; however, please note that adding new entries may result in changes to the SST Total Payable amount, which could differ from the previously submitted figure.

Refer attachment for PDF file