While helping a few businesses with filing, I kept running into the same handful of GSTR-1 upload errors. Sharing what I've understood of the causes, and would like to hear which ones others see most.

RET191150 — wrong tax head. CGST+SGST on what the portal treats as inter-state, or the reverse. Total tax is often identical either way, which is why it passes a manual look and fails the upload. Usually a buyer whose GSTIN is in one state with delivery to another.

RET191205 — tax doesn't reconcile. Taxable value × rate doesn't match the tax declared. Rounding applied per line and again at invoice level, or a discount applied after tax instead of before.

RET191115 — invoice number. Max 16 characters under Rule 46(b), letters/digits/hyphen/slash only. Concatenated branch+year+sequence overruns it.

RET191113 — invalid GSTIN. Often just uploading to the wrong client account when handling multiple GSTINs.

Two questions for the group:

  1. Which of these costs you the most time each month?
  2. Has anyone found a reliable way to catch them before generating the JSON, rather than on upload day?

Happy to share more detail on any of them.