Issuing a debit note to charge an additional amount in SamBooks
7 min read
Unlike a credit note, which reverses, a TD05 debit note adds an amount to an invoice you've already issued: a price adjustment, a surcharge, an accessory expense you forgot. It's its own document, with its own numbering and its own due date.
What this is for
When you realize, after already sending an invoice to SDI, that the customer owes you more — not less — the tool is the debit note: a TD05 document linked to the original invoice, which adds new lines instead of reversing existing ones. It isn't a correction to the invoice (which by now is a final fiscal document you can no longer touch): it's a second, independent document that sits alongside the first.
Before you start
You can only issue a debit note if the original invoice has reached a final status: "SDI Accepted," "Delivered," "Delivery failed," or "Paid." It must be a genuine invoice: you can't issue a note against a credit or debit note that's already been issued.
When you actually need a debit note
- The invoice is still "Draft" or "Ready": no debit note needed. Fix the amount directly with "Edit," since the document has no fiscal value yet.
- The invoice is "Rejected by SDI": no debit note here either. The document was never finalized: you fix and resend it (or delete it), as covered in the guide on a rejected invoice.
- The invoice is in a final status and you need to add an amount: this is the case for this guide — a TD05 debit note.
- The invoice is in a final status and you need to remove or reduce an amount instead: you need the twin tool, the TD04 credit note, covered in its own guide.
How to do it, step by step
1. Open the original invoice and press "Debit note"
Open Sales invoices, find the document in the list, and open it. If the status is one of the final ones, the action bar shows the "Debit note" button, next to "Reverse."
2. Add the surcharge lines
The "New debit note" window opens, with the description: "Additional charge linked to invoice {number}. Add the surcharge lines." Unlike the credit note, here the original invoice's lines aren't pre-loaded: you start from scratch and build the lines you want to charge, each with "Description" (required), "Qty," "Price," and "VAT %." Press "Add line" for every extra item.
3. State the reason for the charge
Fill in the required "Reason for the charge" field (up to 200 characters, e.g. "raw material price adjustment"). Without at least one valid line and a reason, the confirm button stays disabled; if you still try to submit with no lines, the system responds "Debit note with no lines: state the amount to charge."
4. Create the debit note
Press "Create debit note." The confirmation message always says "Debit note created as a draft," but that isn't always literally true: the debit note goes through the same creation engine as any invoice, so if the data is already complete it can be born directly "Ready," not "Draft." Check the actual status on the detail page once you land there: either way, the document has no fiscal effect until you send it.
5. Alternatively: start from "New invoice"
You can reach the same note from Invoices → "New invoice," choosing "Debit note" as the "Document type" (in the "Variation notes" group, alongside "Credit note"). A "Reference invoice" field appears: the picker only shows invoices already sent to SDI. Once you pick the invoice, the button becomes "Proceed" and opens the same "New debit note" window described above.
6. Send the note to SDI
The debit note is its own fiscal document: you send it exactly like any invoice, with the same confirmation dialog, the same local validation of the file, and the same irreversibility, covered step by step in the guide on sending to SDI.
Numbering: the same series as the credit note
Like any invoice, a debit note is born without a number: it only gets one at transmission. It numbers on the same dedicated series with the letter code "NC" used by credit notes — not a separate series for the two variants — keeping the numbering of genuine sales invoices clean and gap-free.
The debit note generates its own due date
This is the most concrete difference from the credit note, which doesn't create its own due dates and instead reduces the outstanding balance of the original invoice. The debit note, going through the same creation engine as a normal invoice, receives its own payment due date — usually the customer's default one — independent and separate from the one on the invoice that triggered the charge. Once you transmit it successfully, SamBooks also creates the linked general-ledger entry, exactly as for any numbered invoice.
Constraints and messages you might encounter
- "Debit note with no lines: state the amount to charge": you haven't added any surcharge line; the document must always carry at least one amount to charge.
- "You cannot issue a variation note against a note (TD04/TD05). Issue it against an invoice TD01/TD24/…": you tried to charge against a credit or debit note that's already been issued: not allowed.
- "Original invoice in status '…': debit note only allowed on invoices in a final status (SDI_ACCETTATA / SDI_MANCATA_CONSEGNA / CONSEGNATA / PAGATA)": the chosen invoice hasn't reached a final status yet, or it's already rejected.
- The "Debit note" button doesn't show up at all: check that the invoice's status is one of the final ones and that it isn't itself already a note.
Ask Sam
You can get the same note from chat: for example, "create a debit note on invoice 45/2026 for a €100 + VAT adjustment, reason: raw material price adjustment." Sam creates it as a draft (or Ready, following the same logic described above) exactly like the "Debit note" button. Even when asking Sam, sending to SDI stays a separate step that you confirm yourself.
If something goes wrong
- I can't find the "Debit note" button: the invoice hasn't reached a final status yet, or it's already a credit or debit note.
- The message says "created as a draft" but the invoice shows "Ready": that's correct, not a bug — the confirmation text doesn't distinguish the two cases, but the actual behavior depends on data completeness.
- I actually want to reduce the amount, not add to it: this isn't the right tool. Use the TD04 credit note, covered in its own guide.
- I got a line wrong after creating the note: while it's still a draft you can fix it like any invoice (Edit); once sent to SDI it's as final as any other document.
Frequently asked questions
How do I create a debit note? Open the original invoice (it must be in a final status), press "Debit note," add the lines to charge, state the reason, and press "Create debit note."
I need to charge a price adjustment to the customer: how do I fix it? Issue a TD05 debit note on the original invoice, with a line for the adjustment and the reason for the charge.
I invoiced less than what was owed: how do I fix it? With a debit note, if the original invoice has already reached a final status. If it's still a draft or ready, fix it directly with "Edit" instead.
What is a TD05 debit note? An independent fiscal document, linked to the original invoice, that charges an additional amount instead of reversing one. It has its own numbering (the "NC" series), its own due date, and gets sent to SDI separately.
What's the difference between a credit note and a debit note? A credit note reverses lines from the original invoice (fully or partially); a debit note adds new lines. The first reduces the invoice's outstanding balance, the second generates its own independent due date.
Does a debit note create a new due date? Yes: unlike the credit note, which doesn't create one of its own, a debit note gets its own payment due date, separate from the original invoice's.
How do I charge accessory expenses after the invoice? Issue a debit note with a line dedicated to the accessory expenses and the reason for the charge in the field provided.
Does the debit note need to be sent to SDI? Yes, always: it's an independent fiscal document with no effect until you send it, through the same procedure as any invoice.
Can I create a debit note on a draft invoice? No: a debit note is only allowed on invoices in a final status (SDI Accepted, Delivered, Delivery failed, or Paid). On a draft, fix the document directly instead.
Why is the debit note already ready while the credit note isn't? The credit note is always born as a draft by design; the debit note, on the other hand, goes through the same creation engine as a normal invoice and can come out already "Ready" if the data is complete — it's an observable behavior, not something you choose at creation time.