Negative accounts payable: vendor balances below zero

Symptom

The AP aging shows vendors at negative amounts — the report claims your suppliers owe you money. Total payables look implausibly low, and the vendor's own statement disagrees with your books, sometimes in both directions at once.

Why it happens

• Double payments — on paper. A bill was paid through the AP module, and the same outflow arrived from the bank feed and was added as a standalone expense. The vendor got paid once; the books say twice, and the second copy drags the vendor negative while also duplicating the expense (/bookkeeping/cleanups-fixes/duplicate-transactions-fix).
• Double payments — for real. The bill got paid by check and then again by autopay. Money actually left twice; the vendor holds your cash.
• Unapplied vendor credits. A return or price adjustment was entered as a vendor credit but never applied to a bill.
• Payments recorded with no bill. Bills paid outside the system (autopay, the owner's personal card) get recorded as bill payments without an underlying bill, or the bill exists only in the vendor's records.

The fix

1. Filter the aging to negatives and pull each vendor's transaction detail.
2. Get the vendor's statement for anyone material. Your books versus their statement settles which payments and bills are real — this is the AP counterpart of a bank reconciliation.
3. Remove paper duplicates. Where the feed added a second expense for a payment the AP module already recorded, delete the standalone expense and match the feed line to the bill payment. Confirm the bank reconciliation still holds.
4. Apply unapplied credits to open bills through the pay-bills or apply-credits screen. Application, not journal entry.
5. Enter the missing bills. For payments recorded without bills, create the bill and link the payment, so the expense lands in the right category and period rather than living as a raw debit to AP.
6. Chase real double payments. Confirm on the bank statement that cash left twice, then request a refund or credit. Until it resolves, the balance is genuinely an asset — reclassify it so the AP aging tells the truth:

Account	Debit	Credit
Vendor refunds receivable (other current asset)	980
Accounts payable — Vendor		980

Reverse when the refund arrives and deposit it against the receivable. If the vendor issues a credit instead, reverse and apply the credit to the next bill.

7. Handle owner-paid bills properly. A bill the owner paid personally is a contribution, not a mystery:

Account	Debit	Credit
Accounts payable — Vendor	450
Owner's contributions (equity)		450

Recorded as a bill payment from an owner-funds clearing account in most software; the effect is the entry shown. The reverse habit — business paying personal bills — is its own cleanup: see personal-expenses-in-books.

Owner-money mixing generally is covered in /bookkeeping/cleanups-fixes/personal-expenses-in-books.

How to prevent it

• Every payment routes through its bill. If the bill is in the system, pay it there; if a payment arrives in the feed first, match it, never add it.
• Enter autopays as recurring bills so the feed always has something to match.
• Apply vendor credits the day they're entered.
• Scan the aging for negatives at every close, alongside the AR mirror-image check in /bookkeeping/cleanups-fixes/negative-accounts-receivable. Thirty seconds a month buys you an AP report a lender can actually read.