On paper, the OSS return is a deadline every three months. In practice it’s a continuous cycle: sales from different channels, warehouse movements, returns, rate updates, reconciliations. Without a precise routine, every quarter becomes an obstacle course.
The reference scenario
To make this article concrete, let’s work with a typical seller:
- Active channels: Amazon EU (FBA with stock in IT and DE), Shopify, eBay.it
- Main countries: IT, DE, FR, ES, PL
- Scheme: standard OSS (exceeds €10,000 of cross-border sales)
- Structure: individual seller or small limited company, external accountant filing the OSS return
Timeline: what to do each month of the quarter
| Stage | When | Concrete actions |
|---|---|---|
| Setup | Day 1 of the quarter | Check that automatic imports from Amazon/Shopify/eBay are active and up to date |
| Month 1 import | End of month 1 | Download and import the Amazon VAT Transaction Report for the month just closed. Same for eBay and Shopify. |
| Threshold check | End of month 1 | Check the YTD total of cross-border B2C sales. Are you close to the €10,000 threshold? |
| Month 2 import | End of month 2 | Same process as month 1. Check that no countries have disappeared compared to the previous month. |
| Anomaly check | Mid-quarter | First look at the per-country report: odd rates? Missing countries? Unexpected spikes? |
| Month 3 import | End of month 3 | Final import + full coverage check: all three months, all channels. |
| Pre-closing | Day 1 after the quarter ends | Generate the aggregated report, check the credit notes, verify per-country totals. |
| Handover to accountant | By the 20th of the following month | Structured folder with the OSS report, original files and a cover note. |
| Return filed | By the 30th of the following month | The accountant files the return and arranges the OSS VAT payment. |
For details on what to include in the accountant handover: How to prepare your accountant for the OSS return.
Month 1: acquisition and normalisation
At the start of the quarter, sales begin and data piles up on each platform. The classic mistake is ignoring this stage, thinking you’ll catch up on everything at the end of the quarter.
What to do concretely:
- Set up an automatic monthly export, or put a reminder in your calendar to manually download the reports by the 5th of the following month;
- Import into VATManager and run currency normalisation (GBP → EUR, SEK → EUR);
- Check that all active channels are included — eBay in particular is often forgotten;
- First threshold check: sum up cross-border B2C sales since the start of the year. If you’re close to €10,000, flag it to your accountant.
Month 2: trend and anomaly checks
The second month is the right time for the first qualitative review: you’re not closing the quarter yet, so you have room to fix any issues.
What to check:
- Comparison with the same month of the previous quarter: changes > 40% in a country are a signal worth investigating;
- Unexpected rates: a country with a 0% rate on physical goods needs immediate checking;
- FBA countries: if Amazon has moved stock to a new country, you might have sales with a
SELLER_ADDRESS_COUNTRYdifferent from IT — those sales don’t go into OSS but into a separate local return.
To understand how to read anomalies in the data: Anomaly detection on VAT reports: what it’s for.
Month 3: pre-closing and final check
In the last month of the quarter, the focus shifts to data completeness. Three questions to answer:
- Time coverage: have all three months’ reports been imported, for all channels?
- Consistent countries: are there countries present in the previous quarter that I don’t see in this one? Why?
- Reduced rates: did I sell reduced-rate products in France (5.5%), Spain (4%), Germany (7%)? Were they classified correctly?
If everything is in order, generating the final OSS report should be a matter of minutes.
Typical seasonal issues by quarter
Some problems recur in specific times of the year:
Q1 (January–March)
- Black Friday and Christmas returns arrive mostly in January: check that all January REFUNDs are included in the Q1 aggregation. A high volume of returns reduces the OSS taxable amount, but it must be declared in the quarter in which the return happens, not the one of the original sale.
- Amazon’s year-end: Amazon can send December accounting adjustments even in January. Check that the December VAT Transaction Report (for Q4) and the January one (for Q1) don’t overlap.
Q2 (April–June)
- Annual threshold review period: by mid-year you already know whether you’re heading towards figures that justify or require additional local VAT registrations.
- First summer campaigns: if you launch promotions that increase volumes in specific countries, monitor local registration thresholds (for those not using centralised FBA).
Q3 (July–September)
- First Prime Day sales: July spikes can create anomalies in the reports. Check that July’s VAT Report is complete and not truncated.
- Increased sales towards Northern Europe (SE, FI, DK): check the correct rates for those countries.
Q4 (October–December)
- Black Friday concentrates sales into a few days: November’s VAT Transaction Reports are often much bigger than usual. Check the file isn’t truncated during download.
- Q3 deadline on 31 October while Q4 has already started: keep the two quarters strictly separate in your imports.
What goes wrong (and how to avoid it)
Problem 1: a forgotten channel Reaching the end of the quarter and realising eBay or your own website weren’t included in the imports means having to reprocess everything. Solution: a fixed checklist with all active channels, to check at the start of every quarter.
Problem 2: a truncated Amazon VAT file Amazon has a size limit on files downloadable from Seller Central. Reports with many transactions can be silently cut off. Solution: compare the number of rows in the file with the number of orders for the period from Seller Central.
Problem 3: unconverted currency Sales on Amazon UK are in GBP. If imported without conversion, the EUR taxable amount is wrong. Solution: set up the ECB rate or a fixed rate agreed with your accountant before the quarter starts.
Problem 4: a new FBA warehouse not communicated Amazon can activate stock in a new FBA country without explicit notice. If you miss it, you declare in OSS sales that actually require a local VAT number. Solution: check Amazon’s FBA panel monthly for changes in storage countries.
📎 Learn more: Quarterly OSS export — an operational checklist — How to read a per-country VAT report — Managing Shopify and Amazon in the same VAT workflow — eBay sellers in Europe: how to organise your VAT data
Frequently asked questions
When should I start preparing the quarter’s OSS return? During the quarter, not at the end. Month 1 is for setting up recurring imports, month 2 for checking trends and thresholds, month 3 for pre-closing. Reaching the day after the quarter ends with already-organised data means having 3-4 comfortable weeks for exporting and handing off to your accountant.
What happens if halfway through the quarter I realise I’ve exceeded the €10,000 OSS threshold? You must apply the customer’s country’s VAT rates starting from the sale that crossed the threshold. Previous sales (below threshold) are declared with Italian VAT. Handling this split manually is risky: using software that automatically tracks the threshold being crossed eliminates this problem.
How do I handle Black Friday returns that arrive in January within Q1? Returns are declared in the quarter in which they occur (Q1), not the one of the original sale (Q4). A high volume of returns in January reduces Q1’s OSS taxable amount. This is correct and normal, but make sure all REFUNDs are included in the right quarter’s aggregation.