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Ato isolado or opening activity? 5 rules to decide before you invoice
Step Inside Accounting · Practical guide
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1. Understand what an ato isolado is and when you can use it
An ato isolado is a service or a sale carried out occasionally by someone who does not have an open activity: a training session given once, a design project for a company, a one-off consultancy job. There is no maximum amount – what matters is that it is a single transaction, with no intention of repeating it.
You can only use it if:
- you do not have an open activity with the Tax Authority;
- it really is an occasional transaction;
- you have not closed an activity this year or the previous year.
2. Issue it on the Portal das Finanças
The ato isolado is issued on the Portal das Finanças, under Cidadãos > Faturas e Recibos Verdes > Emitir, just like a normal recibo verde. You choose the type of document – invoice, invoice-receipt or receipt – and indicate that it is an ato isolado.
You need the client’s details (name and NIF), a description of the service and the amount. If there is VAT to pay, the Portal generates the payment slip as soon as you issue the ato isolado.
3. VAT: no €15,000 exemption here
This is the point that surprises people most: the ato isolado does not benefit from the VAT exemption up to €15,000. If the service is located in Portugal, you charge VAT (23% in mainland Portugal), even if the amount is small.
The VAT must be paid to the State by the end of the month after the one in which you issue the document, using the payment slip the Portal generated. Agree the price with the client with this in mind: if you agree “€1,000” without mentioning VAT, you may be the one who pays the difference.
4. IRS and Social Security: what changes (and what does not)
The amount of the ato isolado is self-employment income and goes in your IRS return for the following year, in Annex B (Anexo B). If the client has organised accounting, it may have to withhold IRS; as the amount is below €15,000, you can claim the withholding exemption when you issue it. If this is your only income in the year and it is below four times the IAS (the social support index, which is €537.13 in 2026), you may not even have to file a return.
The ato isolado does not benefit from the coefficient reduction that applies when you start an activity. Even so, it can be the best option if you started working at the end of the year. If you open activity in November or December, you use up your first year of the reduction with very little invoicing. If you issue an ato isolado for that work and open activity in January, you get the reduction for a full year.
For Social Security, as a rule, an ato isolado does not give rise to contributions. The exception is work done for your employer or for a company in the same group: in that case, contributions are due.
5. Know when it is better to open activity
A second transaction in the same calendar year already requires you to open activity. Using repeated atos isolados to avoid that step is a real risk: the Tax Authority may treat it as an undeclared activity, with VAT to settle and fines.
Opening activity usually pays off when:
- you already know you will have more jobs, even if they are spread out;
- you work with private clients and the VAT exemption up to €15,000 makes you cheaper;
- it is your first activity and you want to use the Social Security exemption and the IRS reduction for new activities;
- you want to invoice regularly, without deciding case by case.
Example
Pedro is employed and, in March, builds a website for a company with organised accounting, for €1,000. He does not have an open activity and does not expect to repeat it, so he issues an ato isolado:
- service value: €1,000
- VAT (23%): €230
- invoice total: €1,230
- IRS withholding: €0 (he claims the exemption, because the amount is below €15,000)
- VAT to pay to the State: €230, by the end of April
The following year, he declares the €1,000 in Annex B of his IRS return. He does not pay Social Security, because the company is not his employer. If in September he is asked to build another website, he can no longer issue a new ato isolado: he has to open activity.
Team tip
Before you issue an ato isolado, ask yourself whether it really is a one-off job. If there is a chance of repeating it, talk to us and we will compare the two scenarios: opening activity from the start is often cheaper and saves you a correction later on.
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This article is for information only and does not replace professional advice. Figures and rules are those in force at the date of publication and may change.
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