Debit notes for additional charges and underbilling

A seller debit note can document an agreed increase after invoicing. First establish that the goods or services were supplied and that the added charge follows the agreement.

By My Inventory Items · Practical document guide

Verify the cause of underbilling

Compare the order, rate agreement, delivery record and invoice. Distinguish a price error from a new supply: a separate new order may need its own invoice rather than an adjustment to an unrelated sale.

Obtain and retain the supporting approval

For a project extension, link the signed change order and time records. For omitted freight, retain the agreed freight terms. A newly generated note cannot substitute for evidence of the agreed price.

Reconcile without duplicating the charge

Bill the omitted difference only. Keep prior payments allocated, show the debit separately on the account and confirm that a replacement invoice has not already included the same amount.

Worked example

An original £1,200 invoice has £400 paid. Approved extra services of £300 plus illustrative £60 VAT create a £360 debit note. The balance becomes £1,200 + £360 − £400 = £1,160.

Illustrative arithmetic, not a customer case study.

Frequently asked questions

Can a debit note replace approval for extra work?

No. Keep the agreement or change approval supporting the charge. Resolve disagreements before describing a disputed addition as accepted.

Official sources and scope

The previews use UK-style GBP and VAT details. HMRC sources cover UK invoice adjustments. The GST guide references India’s CGST Act section 34. Commercial buyer claims and supplier tax documents have different roles. Source links checked on 17 October 2026.

Debit note guides

Debit note format, fields and calculation example

Prepare a debit note with issuer details, original invoice references, approved additional charges, tax and a clear total.

Buyer debit notes for purchase returns and shortages

Track buyer debit memos as supplier claims, document shortages and reconcile accepted supplier credits without double counting.

Debit note accounting examples and reconciliation

See simplified seller debit and buyer claim examples, receivable and payable effects, and controls against duplicate accounting entries.

GST debit note: undercharges, invoice links and records

Understand supplier debit notes under CGST section 34, invoice undercharges, GST fields and supporting reconciliation records.

Give every adjustment a clear record.

Enter your own details in the free debit note generator. It offers GST fields and browser print or PDF output in its own layout. Review the tax fields for your transaction.

Create a debit note

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