You can generate TRAN 1 on FIFO basis using following steps (product wise data):
Step 1: GST Menu- GST reports- Update Stock History option to collect purchase invoice no and date from last years data. Please enter last year companies in System Parameters option.
Step 2: GST Menu- GST reports-Generate TRAN 1 (FIFO).
Due date for filing TRAN 1 is Oct. 31 2017.
If you have multiple principals data, please repeat above steps for all principals. Then do following step.
Export TRAN 1. It will create excel file with multiple sheets in the given path. These sheets contain detail used for generating TRAN 1, Summary sheet to be filled in 7(a) of TRAN 1 and summary sheet to be filled in 7(c) or 7(d) as guided by your tax consultant. You have to login to GSTN and enter these details manually. But it is not difficult as generally just 10-12 lines are there. Please be sure to type everything correctly.
Unfortunately Govt has not provided update in offline tool yet.
Please download attached file for detailed guidance for generating TRAN 1 for batch wise actual basis data. It requires you to generate stock valuation entry as on 30 June 2017 as an additional step. Then Update stock history and then generate TRAN 1 (Actual basis)
Hope it helps
SWIL TEAM