In standard Odoo Accounting, the Pay button opens the payment wizard which defaults to the full outstanding amount. While the amount field is editable, the workflow is designed around full settlement and lacks visibility into the per-invoice breakdown when paying several invoices at once.

This creates friction for real-world payment scenarios:

• Customer pays a fixed instalment - e.g. 40% deposit on a large project invoice
• Partial settlement with write-off - accept $800 in full and waive the remaining $200 as a discount
• Multiple invoices, different partial amounts - pay $5,000 against Invoice A and $3,000 against Invoice B in one session
• Vendor pre-payment - pay part of a supplier bill now and schedule the rest for later
• Bad-debt write-off on partial - collect what's recoverable and write off the unrecoverable portion to a dedicated account

This module adds a "Partial Payment" button to every posted customer invoice and vendor bill. Clicking it opens a dedicated wizard that lists all selected invoices/bills with their full amount, amount due, and an editable Amount To Pay field per line. Enter any partial amount, choose whether to keep the difference open or write it off to an account, then click Validate. The module creates the payment entries, posts them, and reconciles each payment with its invoice automatically. The invoice status updates to In Payment (or Partial after bank reconciliation) and the payment is linked to the invoice for full traceability.

Step 1 - Navigate to the Invoice or Bill

Go to Accounting -> Customers -> Invoices (or Vendors -> Bills for vendor bills). Open a posted invoice whose payment status is Not Paid or Partial.

Step 2 - Click "Partial Payment"

Click the Partial Payment button in the action bar. The wizard opens pre-loaded with the invoice and its full outstanding amount in Amount To Pay.

Step 3 - Set Payment Details

• Journal: Select the bank or cash journal for the payment
• Payment Date: Set the effective date of the payment
• Memo: Optional reference for the payment journal entry
• Currency: Shown in multi-currency setups; defaults to the invoice currency

Step 4 - Enter the Partial Amount

Click the Amount To Pay cell in the invoice row and type the exact amount to collect. The Payment Difference column updates in real time showing what remains. The amount must be greater than zero and cannot exceed the Amount Due.

Step 5 - Choose How to Handle the Difference

When a payment difference exists, the Payment Difference section appears:

• Keep Open - Records a partial payment. The invoice stays open with the remaining balance as an outstanding credit/debit. Future payments (full or partial) can be applied later.
• Mark as Fully Paid - Writes off the difference. Choose a GL account (e.g. bad debt, discount given) and a journal item label. The invoice is fully reconciled and closed.

Step 6 - Validate

Click Validate. For each invoice line, the module:

1. Creates an account.payment record for the partial amount
2. Posts the payment (generates the journal entry)
3. Reconciles the payment's receivable/payable line with the invoice's matching line
4. If write-off is selected, adds a write-off entry to fully close the invoice

After validation, Odoo opens the created payment record.