Cut GST filing from 4 days to 4 hours

01 Hook

Tax teams were burning four full days every filing cycle on work a machine could own.

02 Context

AI Agent Developer Intern at R.K. Tantry & Co. — building automation for financial and tax workflows with a small engineering surface and real filing deadlines.

03 Problem

Manual GST preparation meant copying invoices, reconciling mismatches, and babysitting spreadsheets. Cycle time sat at ~4 days; error risk rose with every handoff.

04 Insight

The bottleneck wasn't 'more AI' — it was a deterministic pipeline with LLM assist only where documents were messy, plus a clear action queue for humans.

05 Exploration

Tried pure spreadsheet macros, then chat-only agents. Macros couldn't read messy invoices; chat agents hallucinated fields without a validation layer.

06 Decision

Owned the trade-off: slower on creative edge cases, faster and safer on the 90% path — OCR/extract → validate → reconcile → human-only exceptions.

07 Solution

Shipped an end-to-end GST automation platform: ingestion, validation, reconciliation, and a dashboard so operators finish filing in hours, not days.

08 Impact

Filing time dropped from 4 days to 4 hours (~95% efficiency gain). The team stopped living in the spreadsheet and started reviewing exceptions only.