In your request, either price or percentage (ratePercent) is required for each InvoiceLineItem. If you set one, do not set the other.
If ratePercent is set for a line item, the line item amount is (ratePercent) x (sum of other line item amount values). If price is set, amount is (quantity) x (price).
What is a recurring invoice?
A recurring invoice is an identical invoice created to receive periodic payments from a customer. These invoices represent an amount that you are owed by a customer for goods and services that you provide.
Recurring invoice numbers are automatically set as the invoice due date in the YYYY-MM-DD format.
You can reduce the total invoice amount with an invoice credit (/CreditMemo.json). Total invoice amount, credit memos, and any remaining invoice amount to be paid or recorded is available with /Crud/Read/ReceivedPay.json.