Preparing the Certificazione Unica (CU) in SamBooks

How to generate the CU for the professionals you paid a fee to with withholding tax applied, and why it sometimes comes out with nobody in it.

What it's for

When you pay a freelance professional's invoice (document type TD06) that carries a withholding tax deduction, your company acts as the withholding agent: you are the one withholding the tax, and you are the one who must certify it to the professional with the annual Certificazione Unica (CU). This guide covers exactly that path: /dichiarativi/cu, reached from the "Certificazione Unica" card in the Tax returns hub.

This is the first of three related paths that look similar but involve different withholdings, and keeping them apart matters:

• Here: you withhold tax from the professionals you pay, and you generate the CU for them.
• If you're looking for where to record the CU forms you receive from your own withholding-agent clients (certifying what they withheld from you), see Recording CU received.
• If you're looking for how to book the withholding a client deducts on one of your issued TD06 invoices, see Booking the withholding tax your clients deduct.

To set the withholding tax on an invoice in the first place (rate, reason code, which lines are subject), see Applying withholding tax, social security fund and stamp duty on an invoice: this guide assumes the professional's purchase invoice already has the withholding correctly set.

Before you start

• You need a write-enabled role — Gestore (Manager) or Amministrativo — to prepare the CU; Visualizzatore (Viewer) and Logistica cannot run the preparation. Browsing the list and downloading the file, on the other hand, need no write permission.
• The professional's purchase invoice must be a TD06, with the withholding tax set in the "Withholding and stamp duty" section of the form — see Recording a purchase invoice.
• The payment of that invoice must be reconciled with a bank transaction, within the year you want to certify.

How to do it, step by step

1. Open Tax returns → Certificazione Unica

From the sidebar open Tax returns, then the "Certificazione Unica" card (subtitle "Annual CU form: TD06 self-employment withholding recipients.", with a count of the CUs already prepared). This opens /dichiarativi/cu, the list of CUs grouped by year.

2. Prepare the CU for a year

At the top right, press Prepare. A confirmation opens: "Prepare Certificazione Unica?", with a Tax year field (proposed as the year before the current one, editable within 2000–2999). Confirming with Prepare generates the CU for that year from the data already recorded; the operation is idempotent: running it again for the same year updates the existing result instead of creating a new one.

3. The condition behind 90% of "nobody shows up" cases

This is the most important point in this guide. SamBooks only certifies payments that are actually reconciled in the bank within the chosen year, on TD06 purchase invoices with withholding tax greater than zero: it's not enough for the invoice to be recorded, it must show as paid — i.e. matched to a reconciled bank transaction — within the calendar year you're certifying. The year comes from the bank transaction date (the value date, or the operation date when there is no value date), not from the invoice date: an invoice dated December but paid in January lands in the following year's CU. If you haven't yet paid (or haven't yet reconciled the payment in Banking) any withholding-bearing invoice for that year, preparing the CU returns an empty result and no card appears in the list for that year: this isn't a bug, it's how the aggregation works. Watch the signal: even on an empty result the confirmation toast is the same one a full CU produces ("Certificazione Unica {year} prepared."), so the only proof the year was populated is the card appearing in the list. Once you reconcile the payment, run "Prepare" again.

4. Read the year card and open the drill-down

Each prepared year appears as a card in the list, with Year, Recipients (how many professionals), Total gross and Total withholding. Clicking the card opens /dichiarativi/cu/{year}, the drill-down with the full table: columns Recipient (name + tax code, or the VAT number when the tax code is missing), Reason, Tax code, Gross, Withholding, plus the three summary totals at the top. The gross figure is the invoice's VAT taxable base, not the invoice total; on a partial payment, both the gross and the withholding for that recipient are calculated proportionally to the share actually paid, not on the full invoiced amount.

5. Running it again doesn't duplicate recipients

If you record a new payment for a professional already present in the CU, or correct upstream data, press Prepare again for the same year: SamBooks updates the existing record for that recipient (same year, same VAT number or tax code), it doesn't create a second one. You don't risk duplicates by re-running the operation.

6. Download the XML file

In the drill-down, the Download XML button appears only if the CU has at least one recipient. The file (BOZZA_certificazione_unica_{year}.xml) contains one element per recipient with their details, the gross amount, the withholding, the reason code and the tax code — its name already carries the "BOZZA_" (DRAFT) prefix, and inside the file's own header there's an explicit notice: it's a structured reconciliation file prepared by SamBooks, not the official electronic filing format of the Italian Revenue Agency. Validation against the Agency's control software, conversion into the telematic format and submission to Entratel remain your accountant's or an authorized intermediary's job — SamBooks does not connect directly to the Italian Revenue Agency. The same notice also appears above the table in the drill-down.

7. The limits to know about: reason code and tax code are both fixed

Today SamBooks sets the CU payment reason code to a single value ("A" — income from self-employment in the habitual practice of a profession or craft) for every recipient, and the same goes for the tax code (always 1040): neither of them can be changed from the page: if a professional falls under a different case (e.g. copyright income or another reason code), the correction should be agreed with your accountant before filing, on the downloaded file. Likewise, there is currently no way in SamBooks to deliver the CU to the recipient (no individual PDF, no email sent from the page): delivering it to the professional, like the submission to the Agency, remains something you arrange outside SamBooks — typically your accountant handles it together with the electronic filing.

8. Cross-check the totals against your withholding F24 payments

The Tax code column in the drill-down always shows 1040 (withholding on self-employment income): like the reason code, it is a fixed value, not derived from the individual invoice. As a consistency check, open your withholding-payment F24s — "Withholdings" group → "Monthly withholdings payment" in Generating and paying an F24 — and compare what you paid during the year against the total withholding shown in the CU for the same period: these are two independent sources (F24 payments on one side, paid-and-reconciled taxable amounts on the other), and a mismatch is worth checking before you hand over the CU.

If something's not right

• I prepare it but the list stays empty for that year — the confirmation toast shows up regardless, so it proves nothing: it means no withholding-bearing TD06 invoice shows as paid and reconciled in Banking with a transaction date inside that year. Check the reconciliation first, then run "Prepare" again.
• My professional/supplier doesn't show up: likely their invoice isn't TD06, has no withholding set, or the payment isn't reconciled yet — see step 3.
• There's no "Download XML" button: that year's CU has no recipients yet; prepare it again after reconciling at least one payment.
• I want to change the reason code (or the tax code) on a recipient: not possible from the page today; note it and correct it with your accountant on the file, or wait for the platform to expose it.
• I need to send the CU to the professional: there's no automatic delivery from SamBooks; deliver it yourself or through your accountant.

Ask Sam

You can ask Sam to prepare the CU ("prepare the Certificazione Unica for 2025") or to list the certifications already generated ("which CUs have I prepared this year, and for which recipients"): Sam uses exactly the same calculations and the same constraints described above — it doesn't bypass either the reconciled-payment precondition or the reason-code limitation.

Frequently asked questions

How do I do the CU for the professionals I paid? Open Tax returns → Certificazione Unica → Prepare, choose the tax year and confirm. You need at least one payment of a TD06 invoice with withholding tax reconciled in Banking during that year.

I prepared the CU but no recipient shows up, why? Because SamBooks only certifies reconciled payments: the withholding-bearing TD06 invoice must be recorded and paid, with the bank transaction matched and reconciled, within the year you chose.

Do I need to have paid the invoice for the CU to show anything? Yes: recording it isn't enough, you need the payment reconciled in Banking within the tax year.

Why doesn't my consultant show up in the CU? Same reasons as above: the invoice isn't TD06, the withholding isn't set, or the payment isn't reconciled yet.

How do I download the Certificazione Unica file? From the year's drill-down, "Download XML" button (visible only if there are recipients).

Does SamBooks send the CU to the Italian Revenue Agency? No. The downloadable file is a reconciliation report, not the electronic filing: submission to Entratel remains your accountant's or an authorized intermediary's job.

How do I deliver the CU to the professional? SamBooks currently has no automatic delivery to the recipient: you or your accountant arrange it outside the platform.

Can I change the reason code on the Certificazione Unica? Not from the page: today it's fixed at "A" for every recipient, just as the tax code is fixed at 1040. Any correction should be agreed with your accountant on the file.

If I redo the CU, do recipients get duplicated? No: running "Prepare" again for the same year updates recipients already present, it doesn't duplicate them.

Do the CU totals match the withholding F24 payments? They should match if you've paid regularly: compare the drill-down's total withholding against your "Withholdings" F24s for the same period, tax code 1040.

What's the difference between CU issued and CU received? The issued CU (this guide) is the one you generate for the professionals you paid withholding tax to. The received CU is the one your withholding-agent clients send you, when they're the ones withholding tax on your invoices: it's recorded in Recording CU received.

Related features

• Recording CU received and checking the gap against your entries — when you're the one receiving a CU.
• Booking the withholding tax your clients deduct — the withholding suffered on your issued invoices.
• Applying withholding tax, social security fund and stamp duty on an invoice — where you set the withholding on the invoice.
• Recording a purchase invoice — where you record the professional's TD06 invoice.
• Generating and paying an F24 — to cross-check the withholding payments.