If you sell digital services, SaaS or other electronically supplied services to consumers in the EU, Stripe Tax can automatically determine the correct VAT rate based on the customer’s country. Simply switching Stripe Tax on is not enough, though. If you are already registered for the Union OSS scheme in Slovakia, that registration also needs to be set up correctly in Stripe.
For a Slovak business registered under Section 7a of the Slovak VAT Act that is not a VAT payer under Section 4, there is an additional complication: Stripe Tax currently cannot model this regime with complete accuracy. This article therefore also shows the adjustment you need to make.
This guide assumes you already hold a valid Union OSS registration with the Slovak Financial Administration. Adding the registration in Stripe does not replace registering with the tax authority.
What Union OSS does
Union OSS allows a business established in the EU to pay VAT on certain B2C supplies to other member states through a single member state of identification.
For electronically supplied services, the place of supply to a consumer is generally the customer’s country. A Slovak SaaS provider can therefore, for example, charge German VAT to a German consumer and Czech VAT to a Czech consumer, and then report these transactions through its Slovak Union OSS return.
For services, however, Union OSS does not cover the member state in which the supplier is established. The European Commission states that services provided to private customers in the country where the supplier has its business establishment or a fixed establishment are not included in Union OSS. You can find more information on the VAT e-Commerce – One Stop Shop website.
Check your Stripe Tax settings
First, open:
Settings → Tax → Business information
Under Head office, you should see:
Slovakia
Stripe uses the Head office as the place where your business is located for tax purposes, and this setting feeds directly into tax calculations. Stripe describes the process in its Set up Stripe Tax documentation.
Also check the Preset product tax code. For a typical SaaS product, the relevant Software as a Service category should be selected. The Tax code matters because Stripe uses it to decide how a given product should be taxed in each jurisdiction.
Add your Union OSS registration
In the Stripe Dashboard, open:
Tax → Locations → Register and file
Then select:
Start collecting tax → Slovakia → I’ve already registered → Union One Stop Shop
If your OSS registration is already in effect, you can start collecting tax immediately. If the registration only takes effect at a future date, choose Schedule tax collection and set the date from which it is effective.
For example, if your OSS registration is effective from 1 October, set 1 October as the start date.
Stripe supports Union OSS as a separate tax registration type, oss_union. This is not the same as a standard domestic VAT registration (standard). Stripe describes the registration types in its Manage your registrations documentation.
Once confirmed, the following will appear under:
Tax → Locations
something like:
Slovakia Union OSS — Collecting tax
Stripe can then automatically calculate VAT based on the consumer’s country for relevant B2C transactions.
Watch out: Section 7a without Section 4 registration
This is where an important Slovak peculiarity comes in.
A business in Slovakia can be identified for VAT under Section 7a, use Union OSS and at the same time not be a domestic VAT payer under Section 4.
In that case, for a SaaS service, for example:
| Customer | Typical outcome |
|---|---|
| Slovakia, B2C | no Slovak VAT, if the supplier is not a VAT payer under Section 4 |
| Germany, B2C | German VAT via OSS |
| Czech Republic, B2C | Czech VAT via OSS |
| Austria, B2C | Austrian VAT via OSS |
| EU B2B with a valid VAT number | reverse charge, depending on the circumstances |
The problem is that Stripe Tax currently cannot natively represent the combination of Slovak Section 7a + Union OSS + no domestic registration under Section 4.
After you activate Slovakia Union OSS, Stripe Tax may therefore calculate Slovak VAT for a Slovak B2C customer, even though such a domestic transaction does not belong in Union OSS.
The solution is a tax customization.
Create a rule for Slovakia
Open:
Settings → Tax → Advanced options
Under Custom tax rules, click:
Create rules
Once this feature is enabled, a Customizations section appears in Stripe Tax. Stripe lets you create a custom rule for a specific product tax code and a specific country, and change a product from taxable to non-taxable, for example. The detailed steps are in the Tax customizations documentation.
Click:
Create customization
And set:
| Setting | Value |
|---|---|
| Product tax code | Software as a Service – Personal Use |
| Effective date | the date from which you want the rule to apply |
| Rule location | Slovakia |
| Tax type | VAT |
| Tax behavior | Non-taxable |
Stripe will then stop charging Slovak VAT for this tax code.
If you also use a separate tax code for Software as a Service – Business Use, create the same rule for that tax code too.
The rule for Personal Use is the most important one, since it is with B2C customers that the problem of Slovak VAT being calculated automatically arises.
Stripe notes that tax customizations are applied by tax code and jurisdiction. They cannot be used to override, for example, reverse charge rules or the determination of the tax jurisdiction itself. Use a tax customization only to adjust a specific tax outcome so that it matches your actual tax regime.
When not to use this override
This setting is not a general rule for all Slovak Stripe users.
If you are a regular VAT payer under Section 4 and are required to charge Slovak VAT on your domestic SaaS sales, setting Slovak SaaS to Non-taxable would be wrong.
The override is relevant precisely in the specific situation where you have, for example:
- a Section 7a registration + Union OSS, but no VAT payer registration under Section 4;
- Slovak B2C SaaS supplies on which Slovak VAT should not be charged.
Likewise, if you later become a VAT payer under Section 4, the rule must be ended or archived as of the date from which Slovak VAT starts to apply to domestic supplies.
Stripe does not automatically take responsibility for changes to the tax treatment covered by active customizations — keeping them accurate is up to you. According to the documentation, if the tax code, location or rate changes, you should archive the rule and create a new one.
Test the setup before going live
Stripe recommends creating a tax customization in a Sandbox first and checking the result on test transactions.
Before deploying to production, we recommend testing at least:
- a Slovak B2C customer;
- a B2C customer from another member state, such as Germany or the Czech Republic;
- an EU B2B customer with a valid VAT number.
With a Section 7a + Union OSS configuration without Section 4, the result for SaaS should look roughly like this:
| Test customer | Expected result |
|---|---|
| Slovakia, B2C | no VAT |
| Germany, B2C | German VAT |
| Czech Republic, B2C | Czech VAT |
This way, you can confirm that Stripe is applying the correct rules before the first real payment.
You can also use Stripe Tax outside Stripe Payments
The Union OSS configuration in Stripe Tax does not have to be limited to card payments processed through Stripe.
Stripe Tax can also be used as a standalone tax engine via the API. This is useful, for example, with a custom checkout, cryptocurrency payments or another external payment flow. Stripe describes this option as the Tax API for off-Stripe payments.
Your application can first send customer and product data to Stripe Tax, receive a VAT calculation based on the customer’s country, and only then create the payment with an external provider. After a successful payment, the calculation can be recorded as a Stripe Tax Transaction.
The advantage is that even payments that did not go through Stripe Payments can use the same tax engine and the same OSS rules.
Summary
For a typical EU SaaS business, the setup itself is fairly simple: you add your Slovakia Union OSS registration to Stripe Tax, and Stripe can automatically calculate the applicable VAT for B2C customers in other member states.
Slovak businesses registered under Section 7a that are not VAT payers under Section 4, however, need to account for a Stripe Tax quirk. The Union OSS registration can lead to VAT being calculated for a Slovak customer as well. In that case, you can adjust the behaviour with Tax customization → Slovakia → Non-taxable for the SaaS tax codes you use.
Any such rule must always reflect the business’s actual tax status.
Stripe Tax features and user interface as of September 2026. Stripe’s tax settings do not replace an assessment of your registration obligations or the OSS registration itself, and this article is not a substitute for individual tax advice.
