What is the scheme for accepting payments?

Question

Payment systems

Good day everyone!
One idea of ​​the project crept into my head and does not let go. I want to implement it, but the financial component is tormenting. Actually on it and a question.
Service (according to my scheme) is an intermediary between the buyer and the seller. The service takes a commission for its services. The service lives on it. Could you tell me how to organize the correct financial scheme?
Faced a number of problems with payment aggregators. Not everyone can withdraw from an internal account to different wallets, for example, YandexKassa only to a bank account. For me, this is also an option, I still plan a "white" service, but according to my scheme, this turns out to be unrealistic. Since the current account will have to report to the tax. And for all the turnover that will pass through the site - this is unrealistic. For example, the buyer replenishes his account with 10,000 rubles. Of these, the seller will get 9500, and the service will get 500 rubles in total. But after all, 10,000 rubles will be credited to the current account and the tax will have to report on this amount. Not to mention the fact that you have to think about how to give the seller 9500.
Tell me where I'm wrong, because the circuit is completely non-working? How do such intermediary sites work, is it really all "black"?

Answer 1

You conclude an agency agreement with sellers
Under an agency agreement, only the commission from the transaction, that is, 500 rubles, and you pay tax on this amount, enters your tax base.
But if your sellers are individuals, then you may have to pay 13% personal income tax from their income, because you can be their tax agent
Here I described in detail How do marketplaces work in Russia?

Answer 2

agency contracts and other verbal and legal turnovers work on white
Yandex TsUPs (or whatever) how long they have worked - years the
best way to find out is to study an already working competitor

Answer 3

Agency contract.
Then taxes are not from the entire turnover, but only from the amount of your commission.

Answer 4

Thanks to those who answered, but for me the scheme still did not become clear.
Let's take fl.ru or better advego.com (copywriting exchange). The exchange acts as an intermediary between the customer and the contractor and leaves a small part for itself, for which it is simply unrealistic to cover everything. Either they are working on the black, or there is some interesting scheme that I overlooked and cannot disclose to myself.
I noticed their payment aggregator - UnitPay. Can you trust? Are they like a physical person or is it like a legal person, we can figure it out on our own?