Intra Account is a Push & Pull payment method supported by the Solid platform. Money movement between Sub Accounts are basically Intra Account (On-Us) transactions. Steps to originate an Intra Account (On-Us) payment transaction:
1

Create Counterparty

Via the Dashboard or the API, Create a Counterparty with the beneficiary account details in the intra_account sub-object.
2

Originate an Intra Account (On-Us) Transaction

Via the Dashboard or the API, Originate an Intra Account Push (where money is pushed to another Sub Account) or Originate an Intra Account Pull (where money is pulled from another Sub Account)
3

Pass Parameters

Pass the necessary parameters (originating sub_account_id, counterparty_id, amount) and other optional parameters as needed.
{
  "sub_account_id": "sub_bda1e562657c41e553104b10aad3fe70",
  "counterparty_id": "ctp_8e5541c8a9e50c3af3b0daacf9175130",
  "amount": "4570.00",
  "description": "May Salary",
  "external_reference_id": "123-9088-2"
}
Congratulations, you have now successfully Originated an Intra Account (On-Us) transaction!
Settlement Time: Instant