Fix sundry creditors ageing using purchase bill FIFO
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A R R R Associates
@@ -269,9 +269,9 @@ def sundry_creditors_aging(
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"""Age closing Sundry Creditors using FIFO from the Accounting Mirror.
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The selected-FY closing is reconstructed from the mirror's ledger opening
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balance plus all creditor movements available up to the selected FY end.
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FIFO means the oldest credit lots are settled first; therefore the closing
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unpaid balance is reconstructed from the newest surviving credit lots.
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balance plus all creditor movements in the selected FY. For trade-creditor
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ageing, that closing control is allocated to actual Purchase voucher credits
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from newest to oldest, which is the year-end result of FIFO settlement.
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Voucher dates are normalized before ageing. This is intentionally strict:
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a dated movement that cannot be parsed is not silently treated as an old
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@@ -472,24 +472,73 @@ def sundry_creditors_aging(
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if closing_balance <= 0.009:
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continue
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# True forward FIFO reconstruction. The selected-FY opening balance is
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# the oldest outstanding lot. Every creditor-increasing movement creates
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# a new dated lot; every creditor-reducing movement settles the oldest lot
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# first. The lots that survive at FY end are therefore the actual FIFO
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# composition of the closing balance.
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# FIFO purchase-bill reconstruction.
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#
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# The selected-FY closing balance above is the control total and already
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# includes every debit/credit movement in the party ledger (payments,
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# receipts, sales adjustments, journals, etc.). For ageing of TRADE
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# CREDITOR BILLS, however, only genuine Purchase voucher credits create
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# purchase-bill lots. Under FIFO, settlements clear the oldest purchase
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# bills first, so the year-end closing balance is represented by the
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# newest purchase bills working backwards from FY end. Treating every
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# CR movement as a bill (for example a Receipt credit in a mixed
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# purchase/sales ledger) gives a false bill date and wrong ageing.
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closing_lots: list[dict[str, Any]] = []
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# A Sundry Creditor ledger can legitimately open with either a credit
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# balance (amount payable) or a debit balance (advance / sales-side net
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# receivable in the same party ledger). The earlier FIFO code created
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# a lot only for a positive opening balance and silently discarded a
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# debit opening balance. That inflated the surviving creditor lots by
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# exactly the unconsumed debit opening. Preserve both sides: a credit
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# opening becomes the oldest payable lot; a debit opening becomes a
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# carry-forward that offsets the earliest future creditor credits.
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debit_carry = round(max(0.0, -opening_balance), 2)
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def _is_purchase_voucher(row: dict[str, Any]) -> bool:
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voucher_type = str(row.get("voucher_type") or "").strip().casefold()
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# Tally voucher types can be renamed/extended (e.g. "Purchase GST").
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# The standard and derived Purchase types retain "purchase" in the
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# exported voucher type name.
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return "purchase" in voucher_type
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if opening_balance > 0.009:
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purchase_rows = [
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row for row in fy_rows
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if str(row.get("dr_cr") or "").strip().upper() == "CR"
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and _is_purchase_voucher(row)
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and _money(row.get("amount")) > 0.009
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]
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# Allocate the closing balance to the newest purchase bills first. This
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# is the direct outstanding-lot consequence of FIFO settlement: oldest
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# purchases are deemed paid first, newest purchases remain outstanding.
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amount_to_allocate = closing_balance
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for row in sorted(
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purchase_rows,
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key=lambda r: (
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r.get("_parsed_date") or opening_fallback_date,
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int(r.get("line_no") or 0),
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),
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reverse=True,
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):
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if amount_to_allocate <= 0.009:
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break
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original_credit = _money(row.get("amount"))
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outstanding = round(min(original_credit, amount_to_allocate), 2)
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if outstanding <= 0.009:
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continue
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closing_lots.append({
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"party_name": party_name,
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"source": "Purchase voucher",
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"voucher_date": str(row.get("voucher_date") or ""),
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"voucher_type": str(row.get("voucher_type") or ""),
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"voucher_number": str(row.get("voucher_number") or ""),
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"reference": str(row.get("reference") or ""),
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"original_credit": original_credit,
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"remaining": outstanding,
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"outstanding_at_fy_end": outstanding,
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"paid_subsequently": 0.0,
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"final_payment_date": "",
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})
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amount_to_allocate = round(amount_to_allocate - outstanding, 2)
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# Any closing amount not represented by Purchase vouchers in the
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# selected FY is brought forward / outside the selected FY purchase
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# history. It remains part of the control total and is aged as old.
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# This also keeps the report honest when a party closing balance contains
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# non-purchase credits that cannot be tied to a purchase bill from the
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# current mirror period.
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if amount_to_allocate > 0.009:
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closing_lots.append({
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"party_name": party_name,
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"source": "Opening / brought forward",
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@@ -497,81 +546,19 @@ def sundry_creditors_aging(
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"voucher_type": "Opening",
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"voucher_number": "",
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"reference": "",
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"original_credit": opening_balance,
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"remaining": opening_balance,
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"outstanding_at_fy_end": 0.0,
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"original_credit": amount_to_allocate,
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"remaining": amount_to_allocate,
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"outstanding_at_fy_end": amount_to_allocate,
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"paid_subsequently": 0.0,
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"final_payment_date": "",
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})
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def settle_fifo(lots: list[dict[str, Any]], amount: float) -> float:
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"""Settle oldest payable lots and return any excess debit amount.
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Excess debit is not discarded. In a mixed purchase/sales party
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ledger it represents an advance / receivable that must offset the
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next creditor-increasing credit before a new payable lot is born.
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"""
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remaining_payment = max(0.0, _money(amount))
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for lot in lots:
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if remaining_payment <= 0.009:
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break
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available = max(0.0, _money(lot.get("remaining")))
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if available <= 0.009:
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continue
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applied = round(min(available, remaining_payment), 2)
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lot["remaining"] = round(available - applied, 2)
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remaining_payment = round(remaining_payment - applied, 2)
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return remaining_payment
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for row in fy_rows:
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side = str(row.get("dr_cr") or "").strip().upper()
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amount = _money(row.get("amount"))
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if amount <= 0.009:
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continue
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if side == "CR":
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# Consume any brought-forward / accumulated debit balance first.
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# Only the residual credit creates a creditor FIFO lot.
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if debit_carry > 0.009:
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offset = round(min(debit_carry, amount), 2)
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debit_carry = round(debit_carry - offset, 2)
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amount = round(amount - offset, 2)
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if amount <= 0.009:
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continue
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closing_lots.append({
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"party_name": party_name,
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"source": "Voucher",
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"voucher_date": str(row.get("voucher_date") or ""),
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"voucher_type": str(row.get("voucher_type") or ""),
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"voucher_number": str(row.get("voucher_number") or ""),
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"reference": str(row.get("reference") or ""),
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"original_credit": amount,
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"remaining": amount,
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"outstanding_at_fy_end": 0.0,
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"paid_subsequently": 0.0,
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"final_payment_date": "",
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})
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elif side == "DR":
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excess_debit = settle_fifo(closing_lots, amount)
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if excess_debit > 0.009:
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debit_carry = round(debit_carry + excess_debit, 2)
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# Remove fully settled lots and freeze the surviving FY-end outstanding
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# amounts before any optional follow-up-year settlement is applied.
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closing_lots = [
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lot for lot in closing_lots
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if _money(lot.get("remaining")) > 0.009
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]
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for lot in closing_lots:
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lot["outstanding_at_fy_end"] = _money(lot.get("remaining"))
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fifo_total = round(sum(_money(lot.get("remaining")) for lot in closing_lots), 2)
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fifo_net = round(fifo_total - debit_carry, 2)
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if abs(fifo_net - historical_closing) > 0.01 or abs(fifo_total - closing_balance) > 0.01:
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fifo_total = round(sum(_money(lot.get("outstanding_at_fy_end")) for lot in closing_lots), 2)
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if abs(fifo_total - closing_balance) > 0.01:
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raise AccountingMirrorError(
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f"FIFO movement reconstruction does not reconcile for {party_name}: "
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f"selected-FY closing {closing_balance:.2f}, FIFO lots {fifo_total:.2f}, "
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f"debit carry {debit_carry:.2f}. Refresh the Accounting Mirror for the "
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"selected FY and retry."
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f"Purchase-bill FIFO reconstruction does not reconcile for {party_name}: "
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f"selected-FY closing {closing_balance:.2f}, allocated lots {fifo_total:.2f}. "
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"Refresh the Accounting Mirror for the selected FY and retry."
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)
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closing_lots = sorted(
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