Your invoicing software says the total is ₹47,320. Your accounting platform shows ₹47,289. Both teams swear their numbers are correct. Neither has time to trace 31 rupees through a month's worth of transactions. By month end, the drift has become ₹8,000. By quarter close, you're reconciling manually for days. This is not a rounding error. This is a sync break —a moment where invoice data and GL data diverge and nobody knows where. When invoicing and accounting systems operate separately, data travels through nine handoff points. At each one, a small difference can hide: a tax code that maps differently, a currency conversion that rounds up instead of down, an accrual that doesn't post until the next batch, a write-off that deletes an invoice line but not the GL entry. Each break is invisible until reconciliation day. And each one costs time you don't have. This playbook maps all nine sync breaks, shows you how to spot them before they compound, and tells you which tools catch them in real time. The nine sync breaks: where invoice GL reconciliation fails 1. Tax code mapping misalignment Your invoicing tool has fifteen tax codes. Your GL has seven . When an invoice with code INT-15 (Interstate GST variant) syncs to accounting, it lands in GST-Basic—because that's the only mapping rule that existed when you set up the sync six months ago. The invoice amount hits the GL correctly, but the tax component lands in the wrong bucket. You can't produce a tax report by code. You reconcile it manually, or you live with the error. How to catch it: Pull a sample of 20 invoices from each month. For each one, verify that the invoice tax code and the GL tax code are identical. If even one drifts, your sync is broken. Fix the mapping rule, then retroactively adjust the month's GL entries. 2. Rounding rules diverge between systems Invoice total: ₹10,000.00. GST at 18% = ₹1,800.00. Grand total: ₹11,800.00. But your invoicing tool rounds per-line-item tax. Your GL rounds per-invoice. On a multi-line invoice, one system rounds ₹487.33 up to ₹487, the other down. By the time you sync, the GL total is ₹11,799.87. The difference is 13 paise. On a hundred invoices, that's ₹13. Both systems are doing what they're designed to do. Neither is wrong. And yet the GL doesn't match the invoice total. How to catch it: Check your invoicing tool's rounding settings and your GL's rounding settings. They must be identical. If they can't be made identical, create a dedicated reconciliation account in your GL that absorbs the rounding variance—usually under ₹100 per month. If it's higher, your settings are still mismatched. 3. Multi-currency exchange rates lock at different times You invoice a client in USD on June 1 at ₹83.20 per dollar. On June 15, when the invoice syncs to your GL, the exchange rate is ₹84.10. Your invoicing tool uses the rate at invoice date. Your GL uses the rate at sync date. The invoice shows one amount, the GL shows another—even though the invoice was never paid. Now the invoice is outstanding. When it's paid in July at ₹85.00, the GL realizes an exchange gain. But the gain is booked against a GL amount that never matched the invoice total. How to catch it: For every multi-currency invoice, log both the invoice total and the GL total on the day of sync. If they differ by more than 0.5%, your exchange rate timing is broken. Fix it by configuring your sync to use the invoice date's rate, not the sync date's rate. If your GL won't accept that, create a separate unrealized gains/losses account and reconcile it monthly. 4. Accrual cutoff doesn't sync on the same day On June 30, you accrue revenue for a partially-completed project: ₹35,000. Your invoicing tool recognizes it immediately. Your GL accrues it on July 2 (because the batch process runs then). On July 5, you issue the actual invoice for ₹35,000. Now your GL has ₹35,000 from the accrual and ₹35,000 from the invoice = ₹70,000, even though you only have one genuine transaction. You catch it at month end when you reverse the accrual. But until then, your GL is inflated. How to catch it: Run a daily report comparing accrued revenue (from your invoicing tool) to accrual GL balances. If the GL balance lags by more than one day, your cutoff is broken. Fix it by moving the GL batch process to run the same day as your invoicing software's close-of-day accrual. 5. Credit memo reversal doesn't reverse the tax You issue invoice #2847 for ₹5,000 + ₹900 GST = ₹5,900. It posts to the GL correctly. The next day, you issue a credit memo for ₹2,000 to correct an overcharge. Your invoicing tool reverses the invoice line: ₹2,000 + ₹360 GST. But your GL sync reverses only ₹2,360 to accounts receivable—it doesn't touch the tax account. The tax balance stays at ₹900 instead of dropping to ₹540. Now your GST liability is overstated. When you file your return, you underpay or overpay based on a GL that doesn't match your actual tax exposure. How to catch it: Every time you issue a credit memo,