Reconciliation — Reconciler

"Reconcile the books."

When to use

• Bank vs ledger — "reconcile June's bank statement against GL cash".
• Subledger vs GL — "the AR subledger says 412k, the GL says 405k — why?".
• Processor vs books — "match Stripe payouts to booked revenue".
• Intercompany — "our payable to the sub doesn't equal their receivable from us".
• Any two lists that should agree and don't.

Workflow

1. Load both sides with code (pasted data or CSV/XLSX — never eyeball long columns). Standardize columns (date, amount, reference, description), normalize signs and currency, drop exact re-export duplicates. Record each side's row count and total — these anchor the bridge.
2. Exact pass. Match on amount + date (+ reference when present); remove matched pairs from the pool.
3. Fuzzy pass, rules tightening in order: amount within tolerance (default ±0.01 — widen only with user sign-off), date within window (default ±3 business days), reference/description similarity. Log every fuzzy match with the rule that made it.
4. One-to-many pass. Detect splits and batches (one bank deposit = several ledger receipts) via combination sums inside the date window.
5. Bucket every leftover: timing (legit, will clear — deposits in transit, outstanding checks), missing (no counterpart expected — unbooked fees, unrecorded receipts), duplicate (same item twice on one side), amount mismatch (paired but different — show the delta).
6. Age the unmatched by days outstanding: 0–7, 8–30, 31–60, 60+. Anything over 30 days gets a priority flag.
7. Propose adjusting entries only for genuine book errors (unbooked bank fee, duplicate posting) — full balanced journals in the journal-entry skill's format. Timing items never get forced adjustments.
8. Prove the bridge: side A balance ± each exception bucket = side B balance, computed in code, residual shown. Target 0.00; anything else is stated, never hidden.

Output format

# Reconciliation — <A> vs <B> — <period>

## Bridge
<A> balance                     <amount>
  + timing: <description>       <amount>
  − missing on <side>: <desc>   <amount>
  ± mismatches (net)            <amount>
= <B> balance                   <amount>
Residual: 0.00 ✓  (or: <amount> — UNRESOLVED, see exceptions)

## Match summary
Exact: <n> | Fuzzy: <n> (rules logged) | One-to-many: <n> | Unmatched: <n>

## Exceptions
| # | Side | Date | Amount | Ref | Bucket | Age (days) | Action |
|---|------|------|-------:|-----|--------|-----------:|--------|
| 1 | Bank | <date> | <amt> | <ref> | missing | <n> | book JE-R1 |

## Proposed adjusting entries
JE-R1 — <memo> — Dr <account> <amt> / Cr <account> <amt> (support: <ref>)

## Aging of unmatched
0–7: <n> / <amt> | 8–30: <n> / <amt> | 31–60: <n> / <amt> | 60+: <n> / <amt>

Quality bar

• Bridge computed in code and proves out; any residual stated explicitly, never hidden.
• Matched + exceptions = input totals on both sides — nothing silently dropped.
• Every fuzzy match shows the rule (tolerance / window / similarity) that made it.
• Every unmatched item bucketed and aged — no "miscellaneous" pile.
• Adjusting entries proposed only for real book errors, each as a balanced JE.
• Tolerances and windows stated up front as assumptions.

Example

Invocation: "Reconcile bank-jun.csv against gl-cash-jun.xlsx." Produced: 214 of 220 rows matched exact, 3 fuzzy (±2-day window, logged), 1 split deposit resolved; exceptions: two deposits in transit $5,110.00 (timing) and one $45.00 unbooked bank fee (missing → JE-R1); bridge: bank $88,214.16 + 5,110.00 = $93,324.16 = GL $93,369.16 − 45.00, residual 0.00.

Decision support, not accounting advice — material figures belong with your accountant/auditor.