Every month, someone in your finance team opens two reports: the accounts payable aged trial balance and the AP control account in the general ledger. The totals don't agree. They rarely do. And so begins a few hours, sometimes a few days, of exporting to Excel, sorting by amount and hunting for the difference.
It doesn't have to work like that. An AP to GL difference is almost never random. It comes from a small number of predictable causes, and once you know them you can build a reconciliation that finds and explains them for you.
What the AP to GL reconciliation actually checks
Your AP subledger holds every open vendor invoice, credit and payment. Your general ledger holds a single control account that should equal the sum of all of it. The reconciliation proves the two agree at period end, and explains any difference with evidence your auditors will accept.
The key word is explains. A reconciliation that says "difference: 12,400, under investigation" is not a reconciliation. It is a to-do list.
The six usual reasons it doesn't tie
1. Timing and cut-off
An invoice is entered in the subledger on the last day of the month, but its batch is posted to the GL in the next period, or the other way round. On its own this is harmless, but it has to be identified and listed every month.
2. Manual journals to the AP control account
Someone posts a correction, an accrual or a reclass straight to the AP control account in the GL. The subledger never sees it. This is the single most common cause of a difference that nobody can explain, and it tends to repeat.
3. Unposted or partially posted batches
In systems like Dynamics GP, transactions sit in batches until they are posted. A batch that has posted to the subledger but not through to the GL, or that failed halfway, creates a difference that looks mysterious until you check batch status.
4. Foreign currency revaluation
If you pay vendors in other currencies, the revaluation posted to the GL and the balances held in the subledger can be calculated at different rates or dates. The difference is real but explainable.
5. Voids, credit notes and reversals
A voided payment or a reversed invoice can be dated differently in the subledger and the GL, especially if it crosses a period end.
6. Posting to the wrong control account
A vendor class or setup points to the wrong payables account, so some invoices land in a different account from the one you reconcile. Intercompany vendors are a frequent culprit.
Reconcile at transaction level, not by totals
Comparing two totals tells you that there is a difference. It never tells you why. The fix is to bring both sides together at document level: every subledger transaction matched to its GL entry by document number, amount and date.
Once the data is matched, each unmatched item can be classified automatically into one of the six causes above: a GL entry with no subledger document is a manual journal, a subledger document dated in one period and posted in another is a cut-off item, and so on. What is left after classification is the genuinely unexplained part, and in a well-run process it is zero.
This is exactly the kind of work Power BI and SQL do well, connected directly to your ERP, with no copying and pasting.
What to automate first
- The matching itself. Subledger to GL at transaction level, refreshed from the ERP.
- Classification of differences. Each reconciling item tagged with its cause, so the reviewer reads a list, not a mystery.
- An exception list with owners. Every open item has a name next to it and a date it will clear.
- Commentary and sign-off. The preparer explains the balance where the numbers live, and the reviewer signs off in the same place. That is your audit evidence.
Fix the process, not just the report
Automation finds differences. Good controls stop them from happening. Three changes make the biggest difference:
- Lock the control account. Where your ERP allows it, only the subledger should be able to post to the AP control account. Manual journals go through a clearing account instead.
- Reconcile weekly. A difference found on the 8th of the month takes minutes to explain. The same difference found on day 3 of the close takes hours.
- Give it an owner. Accounts Payable owns the reconciliation, the controller reviews it. Clear ownership stops it drifting.
What good looks like
By day 1 or 2 of the close, the AP to GL reconciliation shows the subledger total, a short list of classified reconciling items, a GL total that agrees, an unexplained difference of zero, a comment from the preparer and a sign-off from the reviewer. The same approach works for AR to GL, fixed assets to GL and bank reconciliations.
If your team is still hunting for the difference every month, that time can come back to you.
Former Global Product Line Finance Director at SLB. 18+ years in finance leadership across Africa, Asia, Europe and the Middle East, building the automation that takes close cycles from days to hours.
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Hazem El Banna · 8 min read