VAT

Ato isolado (one-off transaction): how to issue it and how much VAT and IRS you pay

By Simples IRS teamPublished 11 November 2026Updated 11 November 20266 min read

Who this is for

This guide is for anyone who makes an occasional sale or provides an occasional service, without an open activity, and wants to issue an ato isolado on the Portal das Finanças. If you already have an open activity and issue recibos verdes regularly, this is not your case: use the opening activity guide and the article 53 exemption guide.

The AT says that if you ceased your activity, you cannot issue an ato isolado in the year of cessation or the following year: you have to restart your activity (AT page «Ato Isolado»).

What an ato isolado is

It is an occasional sale or provision of a service. For VAT, you are a taxable person when, independently, you carry out a single taxable transaction under the conditions of CIVA, article 2(1)(a).

The article 53 exemption does not apply to anyone who carries out a single taxable transaction (CIVA, article 53(6)(a)). Even below €15,000, an ato isolado carries VAT at the rate that applies to the transaction, unless it falls under another exemption (for example, CIVA, article 9, such as certain healthcare activities), provided the transaction takes place in Portuguese territory (AT page).

Since 1 July 2025, you do not submit a start of activity declaration just because of an ato isolado, whatever the amount (CIVA, article 31(3), as worded by Decreto-Lei n.º 49/2025, and the AT leaflet «Início de atividade»). The old €25,000 limit for this exemption is no longer in the article.

Step by step on the Portal das Finanças

The documents and the path are those on the AT page «Ato Isolado»:

Log in to the Portal das Finanças with your NIF and password, or with the Chave Móvel Digital.
Open Faturas e Recibos > Emitir (issue) and choose the ato isolado document.
Choose the right type:
- ato isolado invoice-receipt (fatura-recibo), if the date of the transaction and the date of payment are the same;
- ato isolado invoice (fatura), if payment comes later;
- ato isolado receipt (recibo), when you are paid, to settle the invoice.
Enter the VAT rate that applies (on the mainland, the standard rate is 23%, CIVA, article 18) and, if applicable, the IRS withholding.
Issue it, keep the confirmation and, if there is VAT, also keep the payment slip the Portal generates.
Pay the VAT by the end of the following month at the authorised payment points, with the details on that slip (CIVA, article 27(2), and AT page). This is not the quarterly periodic return of the normal regime.
The following year, declare the income in Anexo B of the Modelo 3 return (IRS > Entregar IRS), unless you are exempt from filing (see below).

How much VAT you pay

VAT is calculated on the value of the service or sale, at the transaction’s rate. On the mainland, the standard rate is 23%. You pay that tax to the State by the end of the month after the month in which the transaction was completed (CIVA, article 27(2)).

Example	Base	VAT (23%)	When you pay the VAT
Service of €20,000	€20,000.00	€4,600.00	By the end of the following month
Service of €8,000	€8,000.00	€1,840.00	By the end of the following month

The private or business client pays you the base plus VAT. You keep the base (minus withholding, if any) and pay the VAT to the Finanças.

How much IRS you pay

An ato isolado is category B income. Withholding tax, when it applies, is an advance payment of IRS: a client with formal accounts withholds it when paying you and pays it to the State. For an ato isolado providing services, the rate is 11.5%: CIRS, article 101(1)(c) includes one-off transactions, and the AT leaflet «Início de atividade» gives 11.5% for «atos isolados». The other rates are in the withholding tax guide.

According to the AT page «Ato Isolado»:

No withholding if the amount is below €15,000. In law, what counts is what you expect to receive in the year in category B, the exemption is optional and you must state it on the document (CIRS, article 101-B(1)(a) and (2)).
Commercial, industrial or agricultural activity (not professional) is always exempt from withholding.
If the withholding works out at less than €25, nothing is withheld either (CIRS, article 101-B(1)(d)).

Example 1 — service of €20,000, with withholding

You issue an ato isolado of €20,000.00 to a company with formal accounts. As the amount is over €15,000, there is no exemption: 23% VAT and 11.5% withholding:

Item	Amount
Base (without VAT)	€20,000.00
VAT (€20,000.00 × 23%)	€4,600.00
IRS withholding (€20,000.00 × 11.5%)	€2,300.00
What you receive (base + VAT − withholding)	€22,300.00
VAT to pay to the Finanças	€4,600.00

For IRS, the simplified regime coefficients apply to one-off transactions if gross annual income does not exceed €200,000 (AT page). With the 0.35 coefficient for services not in the article 151 table (CIRS, article 31(1)(c)), €20,000.00 counts as €7,000.00 of income for calculating the tax. The final IRS depends on the rest of your return: use the calculator for an estimate.

Example 2 — below €15,000, no withholding

You issue an ato isolado of €8,000.00 to a company. As the amount is below €15,000, you state the exemption and there is no withholding. The VAT is €1,840.00. You receive €9,840.00 and pay €1,840.00 of VAT by the end of the following month.

Example 3 — withholding below €25

On an ato isolado of €200.00 at 11.5%, the withholding would be €23.00. That is below €25, so nothing is withheld, even if you do not state the €15,000 exemption.

IRS return and exemption from filing

As a rule, you declare the ato isolado in Anexo B of the Modelo 3 return. You do not have to file the return if the annual amount of your one-off transactions is below four times the IAS (€2,148.52 in 2026) and you have no other income, or only income under CIRS, article 71 (CIRS, article 58(2)(b)). The exemption does not cover, among others, joint taxation (paragraph 3 of the same article). The AT summarises the same rule on the ato isolado page.

Common mistakes

Assuming the article 53 exemption: that exemption does not cover an ato isolado (CIVA, article 53(6)).
Confusing the old €25,000 limit with the current rule: since 1 July 2025, the exemption from the start of activity declaration for an ato isolado does not depend on that amount (CIVA, article 31(3)).
Not paying the VAT the following month: the Portal gives you the payment slip when you issue the document; the deadline is the end of the month after the transaction.
Forgetting Anexo B the following year, when you are not under the 4 × IAS exemption.
Issuing an ato isolado after ceasing your activity, in the same year or the next: the AT requires you to restart the activity.

Check the VAT exemption (open activity)

Frequently asked questions

Is an ato isolado exempt from VAT under article 53?

No. The article 53 exemption regime does not apply to anyone who carries out a single taxable transaction (CIVA, article 53(6)). You charge VAT at the transaction’s rate, unless another exemption applies (for example, under article 9).

Do I have to open activity for an ato isolado?

No. Since 1 July 2025, anyone who carries out a single taxable transaction is exempt from the start of activity declaration, whatever the amount (CIVA, article 31(3), and the AT leaflet «Início de atividade»).

By when do I pay the VAT on an ato isolado?

By the end of the month after the month in which the transaction was completed, with the payment slip generated on the Portal das Finanças (CIVA, article 27(2), and the AT page «Ato Isolado»).

Is there IRS withholding on an ato isolado?

Only if the client keeps formal accounts and no exemption applies. The rate for services is 11.5% (CIRS, article 101(1)(c)). The AT waives withholding if the amount is below €15,000, if it is a non-professional commercial, industrial or agricultural activity, or if the withholding works out at less than €25.

Where do I declare an ato isolado for IRS?

In Anexo B of the Modelo 3 return. You do not have to declare it if the annual total of your one-off transactions is below 4 × IAS (€2,148.52 in 2026) and you have no other income, or only income taxed at the article 71 rates (CIRS, article 58(2)(b)).

Can I issue an ato isolado if I ceased my activity this year?

No. The AT says that, in the year of cessation and the following year, an ato isolado is not possible: you need to restart your activity.

Official sources

Every figure on this page comes from these sources (official documents, in Portuguese). Updated on 11 November 2026