By Vaibhav Rane, Founder, Cresolv One
This is part of our GST & TDS Reconciliation Automation Guide.
Input tax credit in India isn't claimed on what you believe you're owed — it's restricted, by rule, to what actually shows up in GSTR-2B. That single fact is why 2A/2B reconciliation isn't optional bookkeeping hygiene; it's the mechanism that determines whether your claimed credit is actually defensible.
GSTR-2A is a dynamic, near-real-time statement that updates as your vendors file their returns — useful for visibility, but a moving target that changes underneath you. GSTR-2B is a static, auto-generated monthly statement, locked as of a cut-off date, and it's the one rule 36(4) actually anchors ITC eligibility to. Reconciling against 2A alone gives you a live picture that can shift after you've already claimed credit against it; reconciling against 2B is what determines what you can actually defend at assessment.
At its core, reconciliation is matching your purchase register — what you recorded as purchases and the tax on them — against what's reflected in 2B for the same period. Mismatches fall into a handful of predictable categories: the vendor hasn't filed at all, the vendor filed late and it landed in a different period, the GSTIN or invoice number doesn't match what you recorded, or the amount is different. Each category needs a different response — a late filing might resolve itself next cycle, while a wrong GSTIN needs the vendor corrected before you can safely claim that credit at all.
The matching itself — comparing potentially thousands of purchase register line items against 2B entries, categorizing mismatches, and flagging exactly which invoices are at risk — is exactly the kind of systematic, high-volume comparison automation does well and manual spreadsheet work does badly, not because people aren't careful, but because the volume makes manual matching slow and error-prone at any real scale. Automated matching also does this consistently every period, rather than becoming a rushed exercise right before a filing deadline.
Matching tells you where the problem is. It doesn't make a non-filing vendor file, or get a vendor to correct a wrong GSTIN on their invoice. That follow-up is still a relationship task — chasing the vendor, explaining what needs correcting, and tracking whether it actually gets fixed before the credit window closes. Automation that just produces a mismatch report without a clear workflow for resolving each one has automated the easy half of the problem and left you with the same manual follow-up as before, just with better visibility into how much of it there is.
For invoices under the e-invoicing mandate, there's a separate validation: does the invoice carry a valid IRN, generated and validated within the required reporting window? An invoice can match perfectly on GSTIN, amount, and invoice number and still carry a compliance defect if the IRN itself wasn't generated correctly or in time — which is why 2A/2B matching and e-invoicing validation need to run as connected checks, not two separate spreadsheets nobody cross-references.
Cresolv One's AP Automation runs GST-ITC checks and validates e-invoicing requirements as part of the standard workflow, with Cresolv DocAI extracting and structuring invoice data so what gets matched against GSTR-2B is accurate from the point of capture — reducing the mismatches that come from data entry errors before reconciliation even starts.
Automation can match faster than any team can manually — but it can't make a vendor file correctly, which is still the part that needs a person. See our AP Automation, Cresolv DocAI.