{
	"ID": "",
	"RefNumber": "",
	"ExternalID": "",
	"PONumber": "",
	"SubTotal": 0.0,
	"SalesTaxAmount": 0.0,
	"TotalAmount": 0.0,
	"BalanceRemaining": 0.0,
	"DueDate": "2019-08-12T00:00:00.0000000-05:00",
	"TxnDate": "2019-08-12T00:00:00.0000000-05:00",
	"ToBePrinted": false,
	"ToBeEmailed": false,
	"ShippingMethod": {
		"ID": "",
		"FullName": ""
	},
	"LineItems": [{
		"Item": {
			"ID": "",
			"ExternalID": "",
			"Name": "",
			"FullName": "",
			"Manufacturer": "",
			"ItemCost": 0.0,
			"ItemPrice": 0.0,
			"SalesTaxCode": {
				"ID": "",
				"FullName": ""
			}
		},
		"Amount": 0.0,
		"Quantity": 0.0,
		"Rate": 0.0,
		"RatePercent": 0.0,
		"ServiceDate": "2019-08-12T00:00:00.0000000-05:00",
		"IsTaxable": false,
		"Class": "",
		"Description": "",
		"InventorySite": {
			"ID": "",
			"FullName": ""
		},
		"InventorySiteLocation": {
			"ID": "",
			"FullName": ""
		}
	}],
	"TermsRef": {
		"ID": "",
		"FullName": ""
	},
	"Other": "",
	"Memo": "",
	"Class": "",
	"SalesRep": {
		"ID": "",
		"FullName": ""
	},
	"ItemSalesTax": {
		"ID": "",
		"FullName": "",
		"TaxRate": 0.0
	},
	"Customer": {
		"ID": "",
		"ExternalID": "",
		"Name": "",
		"FullName": "",
		"JobTitle": "",
		"CompanyName": "",
		"Salutation": "",
		"FirstName": "",
		"MiddleName": "",
		"LastName": "",
		"Suffix": "",
		"BillAddress": {
			"Addr1": "",
			"Addr2": "",
			"Addr3": "",
			"Addr4": "",
			"Addr5": "",
			"City": "",
			"State": "",
			"PostalCode": "",
			"Country": ""
		},
		"ShipAddress": {
			"Addr1": "",
			"Addr2": "",
			"Addr3": "",
			"Addr4": "",
			"Addr5": "",
			"City": "",
			"State": "",
			"PostalCode": "",
			"Country": ""
		},
		"Phone": "",
		"Mobile": "",
		"AltPhone": "",
		"Email": "",
		"Contact": "",
		"AltContact": "",
		"TaxRate": 0.0,
		"AccountNumber": ""
	},
	"LinkedTransactions": [{
		"ID": "",
		"RefNumber": "",
		"Amount": 0.0,
		"TxnType": "",
		"TxnDate": "2019-08-12T00:00:00.0000000-05:00"
	}],
	"Credits": [{
		"ID": "", // [credit memo ID] works on process only - On Select LinkedTransactions list will contain any credit memos
		"Amount": 0.00 // [credit amount to be applied to invoice]
	}],
	"CustomFields": [{
		"FullName": "",
		"Value": ""
	}]
}

Please note when applying credits to Invoices:

Any credits applied will be permanent unless the credit or invoice are deleted in the QBD UI by a user. Any additional credit applied for new or existing credit memos already applied will be in addition to the existing credit amount.
Example: Invoice 1 ($100) has Credit A ($50) applied for $25. Then on a subsequent Process call another $25 from Credit A is applied to Invoice 1. Now Invoice 1 has an open balance of $50 and $50 of Credit A have been applied.
You can apply as many credits to an invoice as long as it balances and the credits have the available credit balance.
On select all transactions, including credit memos, will be included on the LinkedTransactions list not the Credits list. The Credits list is for Processing only.