How to declare VAT under the One-Stop-Shop (OSS and IOSS)

What is it for?

It groups sales to consumers in other EU countries by country, type of supply and VAT rate, and gives you the amounts to fill in the return on the Portal das Finanças. fiscaldoo sends nothing to the AT.

When to use it?

• The company has joined the OSS scheme and sells to private consumers in other EU countries: one return per quarter.
• The company has joined IOSS and sells imported goods up to 150 EUR: one return per calendar month, only with the invoices marked as IOSS sales.
• Do not use it for sales to businesses with a tax number from another country: those go in the recapitulative statement.

Where to find it?

You can also type OSS, IOSS or balcão único in the Search menu box, in the top bar: it opens the return without going through the VAT panel.

Accounting › Declare › VAT › What is there to do with the VAT? › Supporting lists › VAT return of distance sales in the EU (OSS) or VAT return of distance imports (IOSS).

Neither return has its own line in the VAT menu: you reach them through this panel.

Before you start

• Profile: to create and calculate, Certified accountant. The Accountant and the Auditor can only view: the list does not show them the New button and the open return has no Calculate, only Export to Excel and See the invoice lines.
• The company is in the scheme: the Administrator opens the company in Settings › Users & Companies › Companies and, on the PT Localization tab, in the One-Stop-Shop (OSS) group, ticks In the OSS scheme, fills in OSS since and clicks Create OSS taxes. For IOSS, they fill in the IOSS VAT number. In the demo company 30 rates were created, with each country's standard rate as of today. Pending validation by a certified accountant: each country's rates.
• The invoices are issued with the OSS rate of the consumer's country. On the invoice, the notice says “OSS operation: sale to a consumer in Spain. The VAT of that country is due (normal rate in force: 21%), not the Portuguese one, and it goes to the OSS return.”

How to use it

1. Open Accounting › Declare › VAT › What is there to do with the VAT? and click Supporting lists.
2. Click VAT return of distance sales in the EU and then New.
3. Confirm the Period start and Period end (in the example, 01/10/2026 and 31/12/2026). The Due date fills in by itself.
4. Click Calculate.
5. Check the lines against the invoices, in See the invoice lines, and click Export to Excel if you want to keep the amounts.
6. Fill in the same amounts in the return on the Portal das Finanças.

Expected result

In the example, invoice FT D26/34 of €95.00 to a consumer in Spain, with the OSS ES 21 % rate, gives a line Spain · Goods · 21.00 · €95.00 · €19.95. The totals show VAT due €19.95, VAT booked in the accounts €19.95 and Difference €0.00. The Due date is 31/01/2027.

The invoice generated these lines in the ledger:

Account	Debit	Credit
2111 General customers	€114.95
711 Goods		€95.00
2439901 VAT - OSS scheme		€19.95

The Excel file is named oss_2026-10-01_2026-12-31.xlsx.

Pending validation by a certified accountant: the calculated deadline (end of the month after the period), the accounts, the payment of One-Stop-Shop VAT and the separation between sales to consumers and to businesses.

Important notes

• Nothing is sent from here. The return and the payment are made on the Portal das Finanças.
• IOSS sales are only in the IOSS return, and the others only in the OSS one: a sale never appears in both.
• Credit notes for a quarter already declared appear on separate lines, in the Correction of quarter column, by country and original quarter.

Common problems

• Symptom: “The end of the period is before its start. How to fix it: correct the dates.” Cause: the dates are the wrong way round. What to do: correct them and click Calculate again.
• Symptom: “The IOSS return covers one whole calendar month. What happened: the dates 01/10/2026 to 15/10/2026 are not the first and the last day of the same month. How to fix it: choose the first and the last day of the month.” Cause: the IOSS period is always a whole month. What to do: choose the first and the last day of the month.
• Symptom: you do not see New or Calculate. Cause: your profile can only view. What to do: ask someone with the Certified accountant profile to calculate the return.