This is how Tom West has it in his dictionary.

Hope this helps.

contrato oneroso

1. m. Der. contrato que implica alguna contraprestación.

Fuente: La Real Academia



What Is a Counterpurchase?

A counterpurchase is a particular type of countertrade transaction in which two parties agree to both buy goods from and sell goods to each other but under separate sales contracts.

Source: https://www.investopedia.com/terms/c/counterpurchase.asp




--------------------------------------------------
Note added at 1 day 18 hrs (2021-07-31 04:17:58 GMT)
--------------------------------------------------

Oneroso

En las relaciones y negocios jurídicos, lo opuesto a lncrativo (v.); lo que incluye, compensado o no, obligación positiva o negativa.

Fuente: Enciclopedia Juridica

Onerous transactions are troublesome or oppressive, involving more liabilities than benefits, or they impose significant obligations.
It's about an asset withdrawal, in which the basic tax rate is set according to the transactions involving the duties to liabilities which are carried out by the Subject (the person in question) with a third party.

SP: Transacciones onerosas son operaciones que son difíciles debido a que los pasivos negativos puedan ser más que los beneficios de los bienes activos.
Se trata de un retiro de bienes, en el cual la base del impuesto está fijado de acuerdo con las transacciones o las retiradas onerosas, que son difíciles de efectuar debido a las obligaciones de los pasivos. Las transacciones están efectuadas por el Sujeto (la persona en cuestión) con un partido tercero.

I found a website that contains the same wording as your source text (quoting from same thing) that may explain more about it and you may understand it better than I do: here is the quote and URL:

"Esto último mencionado lo podemos validar revisando el articulo 15 del TUO del IGV:

Tratándose del retiro de bienes, la base imponible será fijada de acuerdo con las operaciones onerosas, efectuadas por el sujeto con terceros, en su defecto se aplicará el valor del mercado." - There is a lot of explanation surrounding all this at https://www.noticierocontable.com/cuida-tu-igv-retiro-de-bie...

I'm suggesting "onerous contracts" because this is a similar sounding term with compatible-seeming meaning that exists in English language accounting. I've also found "onerous liability" and "onerous lease provisions," as well as an "operating lease" that may or may not constitute an "onerous contract."

"What is an Onerous Contract?
An onerous contract is a contract in which the aggregate cost required to fulfill the agreement is higher than the economic benefit to be obtained from it. Such a contract can represent a major financial burden for an organization. When an onerous contract is identified, an organization should recognize the net obligation associated with it as an accrued liability and offsetting expense in the financial statements. This should be done as soon as the loss is anticipated."

https://www.accountingtools.com/articles/what-is-an-onerous-...

https://www.significados.com/oneroso/

Onerous contracts are also discussed/explained on page 6 of 8 of this PDF, seems to be a newsletter from an organization called IFRS (International Financial Reporting Standards). https://www.pwc.com/cz/en/ucetnictvi/ifrs/news/2014/ifrs-new...

I hope this helps.

--------------------------------------------------
Note added at 7 hrs (2021-07-29 16:45:19 GMT)
--------------------------------------------------

The only problem is that if they mean "onerous contracts" one wonders why they didn't just say "contratos onerosos" which is used in Spanish.

To be careful, maybe just simply "onerous operations" would be accurate enough although vague. It's just that I don't find the collocation "onerous operations" in an accounting context in English.

I found 1. Operaciones a título oneroso: el valor de transmisión vendrá determinado por la cotización en dichos mercados en la fecha de la transmisión o por el precio pactado cuando sea superior al de cotización. https://www.agenciatributaria.es/AEAT.internet/Inicio/Ayuda/...

--------------------------------------------------
Note added at 11 hrs (2021-07-29 20:30:11 GMT)
--------------------------------------------------

Sorry, forgot to include that in English, "operaciones a título oneroso" would be "transaction for (nominal) consideration," (the "consideration" being a payment or fee.)

"Los Estados miembros podrán asimilar a una entrega de bienes a título oneroso las operaciones siguientes" is translated as: "Member States may treat each of the following transactions as a supply of goods for consideration" (source given by in-context dictionary as http://apertium.eu/data)

See if "Transaction Consideration" (a legal term) fits: https://www.lawinsider.com/dictionary/transaction-considerat...

If nothing else, "operaciones" can be translated as "transactions." "Onerous transactions" probably just means "onerous contracts," though

--------------------------------------------------
Note added at 3 days 5 hrs (2021-08-01 15:10:55 GMT)
--------------------------------------------------

ONEROUS CONTRACT
THELAW.COM LAW DICTIONARY & BLACK'S LAW DICTIONARY 2ND ED.

civil law. One made for a consideration given or promised, however small.