Submitting accurate One Stop Shop (OSS) returns is essential to ensure your VAT is correctly reported and paid to all EU Member States where your customers are located.

If an OSS return contains errors or incomplete information, corrections may be required and, depending on the circumstances, interest or penalties may be applied by the relevant EU Member State(s).

Why Accuracy Matters

Unlike a domestic VAT return, an OSS return may include VAT due to multiple EU countries.

The Italian Tax Authority (Agenzia delle Entrate) receives your OSS return and distributes the VAT information and payments to the relevant Member States.

This means that incorrect reporting can potentially affect more than one country's tax authority.

Common Errors

The most common OSS reporting errors include:

• Reporting sales in the wrong Member State.
• Applying the incorrect VAT rate.
• Missing eligible B2C transactions.
• Including transactions that should not be reported through OSS.
• Duplicate sales.
• Currency conversion errors.
• Incorrect taxable values.
• Missing refunds or credit notes.

What Happens If an Error Is Found?

If an error is identified after your OSS return has been submitted, it is important to notify your hellotax Account Manager as soon as possible.

Unlike many domestic VAT systems, previous OSS returns are generally not amended.

Instead, corrections are usually made in a subsequent OSS return, in accordance with the EU OSS rules.

Your hellotax VAT specialist will advise the correct adjustment method based on the nature of the error.

Late or Incorrect Payments

If the VAT paid does not match the amount declared, or payment is made after the deadline:

• Interest may be charged.
• Administrative penalties may apply.
• The relevant Member State(s) may request additional information or payment.
• Further compliance checks may be carried out.

As each Member State applies its own penalty and interest rules, the financial consequences can vary depending on the country involved.

Repeated Non-Compliance

Repeated failure to comply with OSS obligations may result in more serious consequences.

In certain circumstances, businesses may be excluded from the Union OSS scheme.

If this happens, the business may need to:

• Register for VAT individually in each EU Member State where VAT is due.
• Submit separate local VAT returns.
• Make VAT payments directly to each country.

This can significantly increase your administrative workload and compliance costs.

How to Avoid Errors

To help ensure your OSS returns are accurate, we recommend that you:

✅ Submit all sales data before the reporting deadline.

✅ Ensure the correct VAT rates are applied for each customer country.

✅ Keep accurate transaction and invoice records.

✅ Inform your hellotax team of any business model changes.

✅ Review your OSS figures before submission.

✅ Contact us immediately if you identify an error after filing.

Need Help?

If you believe your submitted OSS return contains an error, please contact your hellotax Account Manager as soon as possible.

Our VAT specialists will review the issue, explain the appropriate correction process, and help ensure your future OSS reporting remains compliant with EU legislation.

I actually think this article is stronger than simply mirroring the domestic VAT version because it explains the key difference with OSS: penalties are not governed solely by Italy. While Italy receives and processes the OSS return, interest, penalties and enforcement are determined by the individual EU Member State where the VAT is due, and corrections are generally made through a later OSS return rather than by amending the original one. Those are two of the biggest areas of confusion for ecommerce sellers, so including them adds real value to the Help Centre.