The P2P Money Trail — every account from PO to payment, and who supplies it

Account sources: OBYC — material's label VENDOR MASTER — the BP record OTHER BOOK — AO90 / conditions / tax TYPED — you, at that moment

First, the word "ledger" in plain words: the General Ledger (G/L) is the company's cabinet of all account-drawers (160000, 191100, 792000…). "Posting" = writing a Dr/Cr line into some drawer. In S/4HANA every such line physically lands as one row in table ACDOCA — the Universal Journal. So "where to post" always means: which drawer number goes on this line — and some address book must supply it.

ME21N — the Purchase Order: a promise, NOT a posting

🚫 No accounting document is created. A PO is only a promise ("we will buy"). Money is untouched — check FB03: nothing.

But the PO already carries the labels the later postings will read: the material (→ its valuation class 3000), the vendor number (→ its recon account), and on special items the account assignment (K: a typed G/L + cost center · A: an asset number). The PO is the envelope; the labels are on it, the money moves later.

MIGO 101 — Goods Receipt: value enters the company

The truck arrives. NOW the first money document is written — both accounts found automatically:

Dr300000 Inventory raw material OBYC · BSX + label 3000₨12,500,000

Cr191100 GR/IR clearing OBYC · WRX₨12,500,000

What is 191100 really? An automatic IOU note: "we have the goods but no bill yet — we owe SOMEBODY ₨12.5M." That's the built-in accrual you learned in Accounting 101. No human chose either account — the material's label did all the work (the 7920/3000 chain).

MIRO — the Invoice: the IOU becomes a real debt to a real vendor

Dr191100 GR/IR clearing (IOU cancelled) OBYC · WRX₨12,500,000

Cr160000 Trade Payables — via the vendor VENDOR MASTER · Recon. Account₨12,500,000

New address book! You never type 160000 in MIRO — you enter the vendor, and the vendor's own master record carries the answer: the Reconciliation Account field you filled once when creating the BP (BP Guide). Plain words: the vendor IS the label; its recon account is the address. Every posting to any vendor flows through its recon account into the G/L — that's how thousands of vendor balances roll up into one Payables line on the balance sheet.

If your invoice had tax, one more book would open here: the tax code on the invoice → tax account (config OB40). Our system posts non-taxable (I0/A0), so this book stays closed.

F-53 — the Payment: the debt dies, the bank shrinks

Dr160000 Trade Payables (debt cleared) VENDOR MASTER · Recon. Account₨12,500,000

Cr113100 Bank main account TYPED · Bank Data in F-53₨12,500,000

Last address book: the bank. In manual F-53 you type the bank G/L (113100) in the Bank Data block — remember the house-bank ladder from Scenario 5. In the automatic payment run (F110), config supplies it instead: house bank + account ID → bank G/L, so no human types it there either.

🧾 After the dust settles — the self-cleaning accounts

Account	GR	MIRO	F-53	Net	Meaning
300000 Inventory	Dr 12.5M	—	—	Dr 12.5M	You OWN iron worth ₨12.5M (balance sheet)
191100 GR/IR	Cr 12.5M	Dr 12.5M	—	0 ✓	The IOU lived exactly from truck to bill
160000 Payables	—	Cr 12.5M	Dr 12.5M	0 ✓	The debt lived exactly from bill to payment
113100 Bank	—	—	Cr 12.5M	Cr 12.5M	You PAID ₨12.5M cash

The two middle accounts net to zero by design — they only exist to bridge time gaps (goods↔bill, bill↔payment). What remains is the honest truth: iron in, cash out. A purchase isn't finished until this table looks like this — that's why every scenario ends with F-53.

📚 All the address books in one table — who tells SAP where to post

Address book	Its "label" (the key)	Supplies	Our live example	Filled by / when
OBYC OBYC	Valuation class + transaction key	Stock, GR/IR, offsets, price differences	7920→792000 · WRX→191100 · BSA→893010	Finance, once at setup — the chain
Vendor master (BP) BP	The vendor number itself	Payables recon account	Mughal Steel → 160000	Whoever creates the BP — one field, once
AO90 OTHER	Asset class	Asset balance-sheet account (acct A POs)	Class 1110 → 11000 Machinery (Scen. 6, lived it)	FI-AA setup, once per asset class
Pricing schema + OBYC keys OTHER	Condition type's account key	Freight / customs accrual accounts	ZCUS → FR3 → customs accrual (Scen. 21, lived it)	Consultant, on the schema row
Tax config (OB40) OTHER	Tax code	Input/output tax accounts	Quiet on our system (I0/A0 non-taxable)	Finance, once per tax code
Typed by hand TYPED	—	K/NLAG PO lines (expense G/L + cost center) · manual F-53 bank	410000 + cost center (Scen. 5) · bank 113100	You, on the document — the only manual door

🔀 Same trail, special POs — what changes at the GR step

PO flavor	GR posts	Account came from	Rest of the trail
Stock PO (this page)	Dr Inventory / Cr GR/IR	OBYC via valuation class	identical: MIRO → F-53
K — cost center (Scen. 5)	Dr Expense 410000 / Cr GR/IR	typed on the PO line (+ cost center)	identical
A — asset (Scen. 6)	Dr Asset (→11000) / Cr GR/IR	AO90 via the asset's class	identical

Notice what NEVER changes: GR/IR in the middle, vendor recon at the invoice, bank at the end. Only the first Dr line — where the value lands — switches address books.

🧠 The whole trail in one breath (interview version)

"A PO posts nothing. At goods receipt, OBYC uses the material's valuation class to debit stock (or the PO's account assignment debits an expense or asset) and credits GR/IR as an automatic accrual. The invoice clears GR/IR and credits the vendor, whose master record supplies the reconciliation account. Payment debits that payable and credits the bank account from manual entry or house-bank config. GR/IR and the payable net to zero — what remains is inventory up, bank down, all of it rows in ACDOCA."

The other two pages of this visual trilogy: 🗺️ MM ↔ FI Map (the overview) · 🔗 The 7920 Chain (the stock-label zoom) — and every broken-chain error lives in the Troubleshooting Center.

💸 The P2P Money Trail — from PO to paid, every number tagged