Applying withholding tax, welfare fund contribution and stamp duty on an invoice in SamBooks
7 min read
Three amounts that add to the calculation on a professional-services invoice: you set the withholding tax line by line, you fill in the welfare fund contribution in its own section, and virtual stamp duty is instead calculated by SamBooks on its own, with nothing for you to do.
What this is for
On a Fee note (TD06) invoice — but also on an ordinary invoice, if needed — you'll find two sections built for anyone invoicing professional services: "Withholding tax" and "Welfare fund contribution." They're independent of each other: you can use one, both, or neither. Virtual stamp duty, the third amount that can appear on an invoice, isn't something you set at all: SamBooks calculates it itself by looking at the invoice's exempt taxable amount.
Before you start
The two sections live in the invoice creation/edit form, below the lines: on a Fee note (TD06) they open by themselves; on any other document type they stay closed but available, one click away.
How to do it, step by step
1. Open the "Withholding tax" section
In the invoice form, the collapsible "Withholding tax" section — with the notice: "For professional/agent fee notes (TD06). SamBooks calculates the amount on the subject lines." On a TD06 invoice you'll find it already open; on other types, press to expand it.
2. Choose the withholding type and reason
In the "Withholding tax" field, choose the type among: individuals (RT01), legal entities (RT02), INPS (RT03), ENASARCO (RT04), ENPAM (RT05), other welfare (RT06) — or leave "No withholding." As soon as you pick a type, the "Withholding rate" and "Payment reason" fields appear, with reasons: self-employment services (A), use of intellectual works (B), profits from participation (C), SDI agent commissions (W), other proceeds (ZO).
3. Mark the lines subject to withholding
With a withholding type selected, every invoice line shows the "Subject to withholding" checkbox: check it on the lines the withholding should be deducted from, leave it unchecked on the ones that don't apply — the notice states it explicitly: "On the lines, check the ones subject to withholding; exclude art. 15 expense reimbursements (advances made in the customer's name and on their behalf)."
4. Read the estimated amount, then the final one
In the form's summary, below the totals, the "Withholding (estimate)" line appears with the amount calculated in real time on the lines you've marked. It's an estimate: the authoritative amount — the one that actually ends up on the document — gets recalculated by SamBooks on save, together with the rest of the totals.
5. Open the "Welfare fund contribution" section, if needed
If you're subject to a professional welfare fund (e.g. an integrative contribution), open the collapsible "Welfare fund contribution" section — on a Fee note it opens by itself. Fill in "Fund type," "Rate %," "Contribution" (the amount, if you already know it) or let SamBooks calculate it from the taxable amount and the rate, "Taxable amount," "Fund VAT %," and, if the contribution has no VAT, the matching VAT nature (mutually exclusive with the rate).
6. Don't set the stamp duty yourself: it's automatic
On a real invoice (not a proforma), you'll never find a field to type in the stamp duty: SamBooks calculates it itself on save, by summing the taxable amount of the exempt or out-of-scope lines. If that sum exceeds €77.47, a virtual stamp duty of €2.00 is added automatically to the totals; below that threshold, nothing appears. Reverse-charge lines (nature N6.x) don't count toward this sum, even at a zero rate: they're taxable transactions with VAT charged to the customer, not exempt ones.
7. Check everything on the invoice detail page
After saving, open the detail page and look at the "Totals" section under the "Details" tab: here you'll find, if present, Taxable amount, VAT, Stamp duty, "Withholding {type} {rate}%," "Welfare fund," and the final "Total document" — these are the definitive amounts, no longer estimates.
If something goes wrong
- I don't see a field for stamp duty: that's correct, there isn't one on a real invoice: SamBooks calculates it itself, and it only shows up in the totals if the exempt taxable amount exceeds the threshold.
- The estimated withholding in the form doesn't match the final one: that's normal, the form shows an estimate; the final amount is recalculated on save, and you can check it on the saved invoice's detail page.
- I selected a withholding type but the amount stays zero: check that you've marked "Subject to withholding" on at least one line; with no lines marked, there's no base to calculate the withholding from.
- The welfare fund's VAT nature field isn't available alongside the VAT rate: they're alternatives, just like on regular lines — you either set a rate, or declare a nature for an exempt contribution, never both.
- I want to set the stamp duty by hand: you can only do that on a fee-note notice (proforma), which is a pre-invoice document that isn't fiscal yet; on a real invoice it always stays an automatic calculation.
Ask Sam
You can ask Sam to compose a fee note with withholding and welfare fund contribution already set — for example, "make a fee note to customer Bianchi for €1,000 plus VAT, with 20% RT01 withholding tax and a 4% welfare fund contribution" — and Sam applies the same fields covered in this guide, including marking the lines subject to withholding. The stamp duty, even when asking Sam, stays always automatically calculated: it isn't a parameter you can specify, not even in chat.
Frequently asked questions
How do I apply withholding tax on an invoice? Open the "Withholding tax" section (it opens by itself on a Fee note TD06), choose the type and the payment reason, then check "Subject to withholding" on the lines it should be deducted from.
How do I set the welfare fund contribution? Open the "Welfare fund contribution" section and fill in type, rate, contribution (or let it be calculated), taxable amount, and the contribution's VAT (or its nature, if exempt).
How do I add stamp duty to an invoice? You don't set it yourself: SamBooks calculates it automatically if the taxable amount of the exempt lines exceeds €77.47, adding €2.00 to the totals.
Why can't I find a field for virtual stamp duty? Because it doesn't exist on a real invoice: it's always an automatic calculation. A manual stamp duty field only exists on the fee-note notice (proforma), a document that isn't fiscal yet.
What's the difference between RT01 and RT02? They're two of the withholding types available in the "Withholding tax" field: RT01 for individuals, RT02 for legal entities.
Do I have to mark every line as subject to withholding? No: mark only the ones that genuinely are. In particular, exclude art. 15 expense reimbursements (advances made in the customer's name and on their behalf), which aren't subject to withholding.
Is the withholding amount I see in the form the final one? No, it's an estimate calculated in real time as you fill in the form; the authoritative amount is on the invoice's detail page after saving.
Can I apply both withholding and a welfare fund contribution on the same invoice? Yes: the two sections are independent, you can fill in one, both, or neither.
Does the welfare fund contribution always have VAT? No: you can set a VAT rate on the contribution, or declare it exempt with a VAT nature — the two are alternatives to each other.
When does the €2 stamp duty kick in? When the sum of the taxable amounts of the invoice's exempt or out-of-scope lines exceeds €77.47. Below that threshold, no stamp duty appears.
Do reverse-charge lines count toward the stamp duty? No: even at a zero rate, lines with N6.x nature are taxable transactions (the customer settles the VAT) and don't count toward the stamp duty threshold.
Can I see withholding, welfare fund and stamp duty together on the invoice detail? Yes: in the Totals section of the Details tab you'll find every amount present — Stamp duty, Withholding with its type and rate, Welfare fund, and the final Total document.