FIZ
AI-PoweredAT-certified Portuguese tax, invoicing, and Social Security automation for sole traders with a built-in AI tax assistant
About FIZ
FIZ handles AT-certified electronic invoicing, Social Security contributions, and VAT declarations for Portuguese sole traders and independent professionals. Every invoice issued through FIZ carries certification number AT nº 3041, meaning it satisfies the Portuguese Tax Authority's legal requirements without any additional steps. The platform calculates Social Security contributions automatically each month and files VAT returns under both the standard domestic regime and the Intra-EU regime for independents selling cross-border within the EU. Prime tiers add an AI tax consultant that fields Portuguese tax questions in plain language and walks users through declaration preparation. The free Base tier covers invoicing only. Paying €9.99/month adds Social Security automation. At €14.99/month you pick either the AI assistant or standard VAT filing — not both. The full stack, including Intra-EU VAT and AI, costs €24.99/month. FIZ claims over 15,000 customers and a zero-fines record on declarations submitted through the platform. FIZ does exactly one thing well: it removes the administrative load of Portuguese self-employment tax compliance for individual operators. It does nothing for accounting firms managing client portfolios, nothing for LDAs or companies, and nothing for anyone outside the Portuguese tax regime. There are no connections to Xero, QuickBooks, or any general ledger system.
Best for
Portuguese sole traders and independent professionals needing AT-certified electronic invoicing, automatic Social Security and VAT calculations, and AI-assisted tax declarations.
Key Features
- AT-certified electronic invoicing (nº 3041)
- Automatic Social Security contribution calculations
- VAT declarations (standard and Intra-EU regimes)
- AI tax consultant on Prime tiers
- Expense tracking and financial dashboards
Pros & Cons
Pros
- AT-certified invoicing (nº 3041) satisfies Portuguese Tax Authority legal requirements — invoices need no supplementary certification steps.
- Permanent free tier covers electronic invoicing with no time limit, useful for sole traders whose only compliance need is issuing compliant invoices.
- Automates monthly Social Security contribution calculations, which sole traders under the simplified regime frequently miscalculate manually.
- Files both standard domestic VAT returns and Intra-EU VAT returns, covering independents who bill clients in other EU member states.
- AI tax consultant on Prime tiers answers Portuguese-specific tax questions and assists with declaration preparation — not generic advice.
- Pricing tops out at €24.99/month for the full feature set, which is low for a country-specific certified invoicing and tax filing tool.
Cons
- Portugal-only with no crossover utility — any practitioner or client outside the Portuguese tax regime gets nothing from this tool.
- Sole traders and independent professionals only — no firm-level features, no client workspaces, no team seats for accountants managing multiple filers.
- The €14.99/month tier forces a choice between the AI assistant and standard VAT filing; getting both requires jumping to €24.99/month.
- No integration with Xero, QuickBooks, or any general-purpose accounting system, so users maintaining a separate ledger must reconcile manually.
- Ratings come from App Store and Google Play only — no G2, Capterra, or TrustRadius data exists to benchmark against comparable tools.
- AI tax consultant is available only on paid Prime tiers; free and €9.99/month users have no access to it.
Frequently Asked Questions
Common questions accountants ask about FIZ.
What does the free plan actually include?
The free Base tier covers AT-certified electronic invoicing only, with no time limit. Social Security automation, VAT filing, and the AI tax consultant all require a paid tier starting at €9.99/month.
Does FIZ integrate with Xero or QuickBooks?
No. FIZ connects directly to the Portuguese Tax Authority and Portuguese Social Security systems. There is no API or native integration with Xero, QuickBooks, Sage, or any general-purpose accounting platform. Data reconciliation between FIZ and a separate ledger is a manual process.
Can an accounting firm use FIZ to manage multiple sole trader clients?
FIZ is built for individual sole traders filing their own taxes, not for accountants managing a client portfolio. There are no client workspaces, multi-user team seats, or firm-level billing structures. An accountant could assist a client using the tool, but FIZ will not replace practice management software.
Does FIZ handle VAT for sales to clients in other EU countries?
Yes. The €24.99/month Auto Pro tier includes the Intra-EU VAT regime, which covers cross-border sales to business clients in other EU member states. Standard domestic VAT filing is available at €14.99/month on the VAT-specific tier.
How does FIZ compare to filing directly through the Portuguese Tax Authority portal?
The AT portal requires sole traders to calculate Social Security contributions manually, issue invoices through a separate certified system, and file VAT returns on their own schedule. FIZ automates all three in one place and holds AT certification nº 3041, so outputs are legally equivalent to direct portal submissions.
Is FIZ suitable for a Portuguese LDA or limited company?
No. FIZ is explicitly built for sole traders and independent professionals filing under the simplified or organised accounting regimes for individuals. LDAs, Sociedades Anónimas, and other corporate entities are outside the scope of the platform.