1. Why there are three mechanisms to "prepay" IGV
Percepción, retención, and detracción are three different systems SUNAT uses to make sure it collects IGV before it reaches the end of the chain — reducing the risk that someone charges IGV to their customer and never files it. All three move money ahead of the monthly return, but they work in completely different ways, and applying the wrong mechanism to a transaction is a common mistake.
2. Percepción del IGV: your supplier charges it to you
Under percepción, a percepción agent (designated by SUNAT — typically fuel sellers, or importers of goods) charges you an extra amount on top of the sale price, in addition to the invoice's normal IGV. That amount collected from you works in your favor: you use it as a credit against your own IGV payable in the monthly return.
The one who suffers the percepción is the buyer — you, if you buy from a percepción agent. The one who collects it and files it with SUNAT is the seller.
3. Retención del IGV: your customer withholds it from you
Under retención, a retención agent (designated by SUNAT — generally large companies) buys from you, and instead of paying you 100% of the invoice, withholds a percentage of the IGV and hands you a comprobante de retención. That receipt is your support for using the withheld amount as a credit against your own IGV payable.
Here the one who suffers the retención is the seller — you, if you sell to a retención agent. It's almost the mirror image of percepción: under percepción you suffer as a buyer, under retención you suffer as a seller.
4. Detracción (SPOT): the "Banco de la Nación" in the middle
The Sistema de Pago de Obligaciones Tributarias (SPOT), better known as detracción, works differently from the other two. It applies to a list of goods and services defined by SUNAT (several services, some specific goods, transport services, among others). The buyer must deposit a percentage of the sale price into a Banco de la Nación account in the seller's name — but that money isn't freely available to the seller: they can only use it to pay their own taxes (IGV, Renta, fines, contributions), not for any business expense.
That's the key difference: percepción and retención generate a direct credit on your return. Detracción generates a separate fund that can only be drawn on to pay taxes.
5. Can more than one apply to the same transaction?
In general, SUNAT didn't design these systems to stack on the same receipt — if a transaction is subject to detracción, retención normally doesn't also apply to it. But since each mechanism has its own list of goods, services, and designated agents, the only way to know for certain what applies to a specific transaction is to check whether the good or service is on the detracción list, whether your customer is a retención agent, or whether your supplier is a percepción agent — not to assume based on a similar transaction.
6. What to do with those funds
- Percepciones and retenciones suffered: filed on the monthly IGV form and applied against the period's IGV payable. If they aren't used up within the month, they carry over to the following periods.
- Detracción funds: used directly from the Banco de la Nación account to pay your own taxes — they don't go through the monthly return as a credit; it's a separate payment circuit.
7. How factsimil handles it
All three mechanisms affect how much cash comes in or out on each sale or purchase, but they don't change how the receipt itself gets issued. factsimil records your facturas and boletas the same as always, and the Accounts Receivable and collections module lets you see the real net amount you collected or paid after percepciones, retenciones, or detracciones — without having to rebuild it by hand in a separate spreadsheet.
If you also keep your accounting in factsimil, those amounts are already reflected in the Libro Diario along with the rest of the transaction.