Before you start

A NIF (Número de Identificação Fiscal) — your tax number, obtained from Finanças or via a representative; non-EU residents may need a fiscal representative until they hold residency
Registered as tax-resident in Portugal once you cross 183 days or establish a habitual home (update your address/residency status at Finanças)
Portal das Finanças online access (password by post, or Chave Móvel Digital / Cartão de Cidadão login) — everything is filed online

Step-by-step

1
Determine residency and register your status
You become a Portuguese tax resident if you spend 183+ days in Portugal in any 12-month period OR keep a home here suggesting habitual residence. Residents are taxed on worldwide income; non-residents only on Portuguese-source income. Update your residential address and tax-residency status on the Portal das Finanças (or at a Finanças desk) so the AT treats you correctly.
OnlineWho: New resident (self or accountant/contabilista)Status takes effect from the day you meet the residency test; address update is immediateFree
2
Check whether you qualify for IFICI ('NHR 2.0') and apply by the deadline
NHR closed to new entrants after 31 Dec 2023 (a 2024 transitional grandfathering aside). Its replacement, IFICI (Incentivo Fiscal à Investigação Científica e Inovação), gives a 20% flat IRS rate on qualifying Portuguese employment/self-employment income plus exemption on most foreign-source income for 10 years — but ONLY for eligible roles: scientific research, higher-education teaching, certified startup staff, and other listed highly-qualified/innovation activities, and you must not have been Portuguese tax-resident in the prior 5 years. Apply through the relevant body (AT, FCT, AICEP, Startup Portugal) by 15 January of the year after you became resident.
OnlineWho: New resident in an eligible activity, usually with a tax adviserApply by 15 January following your first year of residenceFree to apply; adviser fees ~€500-2,000 to assess and file
3
If self-employed, open activity and set up Segurança Social + IVA
Freelancers register an 'início de atividade' on the Portal das Finanças and bill via recibos verdes (green receipts). Most use the simplified regime, where ~75% of services income is taxed (so ~25% is an automatic expense allowance). Segurança Social costs ~21.4% on a 'relevant income' base (70% of services income) — a big line item — but you're EXEMPT for the first 12 months of activity. IVA (VAT) standard rate is 23%; you can stay VAT-exempt under Art. 53 below the turnover threshold (~€15,000 for 2026), otherwise you charge and remit IVA periodically.
OnlineWho: Self-employed / freelancers (often via a contabilista)Activity registration is immediate; Segurança Social billing starts after the 12-month exemption; IVA filed quarterly or monthlyRegistration free; ongoing ~21.4% social security + IRS + 23% IVA where applicable
4
Validate e-Fatura invoices and file the annual IRS return online
First, log into e-Fatura by late February and sort invoices carrying your NIF into categories (health, education, housing, general) to unlock deductions. Then file the IRS return on the Portal das Finanças between 1 April and 30 June. Simple cases (single Portuguese employer, no foreign/rental income) get a pre-filled IRS automático you just confirm — it self-submits if untouched. Everyone else completes Modelo 3 with the right annexes (Anexo J for foreign income, Anexo B for self-employment). AT issues the assessment by 31 July; pay any balance by 31 August.
OnlineWho: All tax residents (self or accountant)e-Fatura by ~end Feb; IRS return 1 April-30 June; pay/refund by 31 AugustFree to file; contabilista typically €60-250 for a personal return

Documents you’ll need

NIF (Número de Identificação Fiscal)
Portal das Finanças credentials (password by post, or Chave Móvel Digital / Cartão de Cidadão)
Proof of income — employer payslips/declaration, or your recibos verdes if self-employed
Foreign income and foreign tax-paid records (for Anexo J and double-tax relief)
e-Fatura validated invoices for deductible expenses
Residency proof and NISS (Segurança Social number) if self-employed
For IFICI: contract/role evidence and certification from the relevant authority

Things most newcomers don’t know

Don't assume you get the old NHR deal — most newcomers no longer qualify for any flat-rate regime at all. IFICI is far narrower: it targets specific scientific-research, higher-education, certified-startup and highly-qualified innovation roles, not 'any remote worker' or retiree.

The 20% headline rate is heavily advertised, but eligibility is role-based and certified by a sector authority (AT, FCT, AICEP, Startup Portugal). Applying when you don't qualify wastes the one-shot 15 January deadline and leaves you on standard rates (to 48%).

Source: PwC Portugal — Tax incentive for scientific research and innovation (IFICI)

For freelancers, Segurança Social — not IRS — is often the painful number, and the 12-month exemption is a planning window.

New self-employed pay no social-security contributions for the first 12 months; after that it's ~21.4% on 70% of your services income, billed monthly regardless of whether a client paid you — which can dwarf IRS at lower earnings.

Source: Segurança Social / gov.pt — self-employed contributions

Validate your e-Fatura invoices before you file — deductions you don't categorise by the February cut-off simply don't count, and IRS automático can quietly auto-submit a return that omits foreign income.

Health, education, housing and general deductions only flow through if invoices carrying your NIF are sorted in e-Fatura. And if you have foreign income (Anexo J) or rentals, the pre-filled IRS automático won't capture it — accepting it as-is can mean an under-declared return.

Source: Portal das Finanças / e-Fatura; gov.pt IRS guidance

Common mistakes to avoid

Assuming the 183-day test is the only trigger — keeping a habitual home in Portugal can make you tax-resident (and taxable on worldwide income) even with fewer days here
Confusing legacy NHR with IFICI: NHR is closed to new arrivals, and IFICI's 20% rate only applies to specific eligible activities — pensions and many remote jobs don't qualify
Missing the IFICI application deadline (15 January after your first resident year) — it's effectively one-shot, and late applications can forfeit the regime
Forgetting Segurança Social as a freelancer, or being surprised when the ~21.4% contributions start after the 12-month exemption ends
US citizens forgetting they still owe US returns plus FBAR/FATCA reporting — the US–Portugal treaty and foreign tax credits prevent double taxation but do NOT remove the US filing duty

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.