u/Hot_Historian_6673

Hello Guys posting here very important Deadlines when it comes to taxes,imi, iuc etc, so dont miss them especially filing IRS which isnt that far now! so add a reminder on your phone! Source Portugal Tax calender 2026

Date	What it covers	What you must do	Who it applies to	If you miss it
16 Feb 2026	Long-duration rental contracts	Communicate contract duration or cessation to AT	Landlords with residential leases of 2+ years	May lose associated tax benefit
2 Mar 2026	e-Fatura invoice validation	Review, register, and classify 2025 invoices in e-Fatura	All tax residents with NIF invoices	Deductions may be lower or misclassified
2 Mar 2026	Household composition	Confirm agregado familiar as of 31 Dec 2025	Anyone with household changes or joint/dependent filing	AT uses prior-year data by default
16–31 Mar 2026	Deduction review and complaints	Check AT’s provisional deduction totals and complain about eligible discrepancies	All tax residents claiming deductions	Deductions may be lower than expected when filing opens
31 Mar 2026	IRS/IVA consignação	Choose whether to allocate 1% of IRS and/or VAT deduction to an eligible organisation	Optional for tax residents	Option is unavailable after the deadline
1 Apr 2026	IRS filing opens	File Modelo 3 or check IRS Automático if eligible	All tax residents required to file	Opening date; no need to file on day one
May 2026	IMI first instalment	Pay IMI using the reference in Portal das Finanças	Property owners	Interest and enforcement risk
30 Jun 2026	IRS filing closes	Submit Modelo 3, confirm IRS Automático, or request an extension before the deadline if eligible	All tax residents required to file	Coima risk under RGIT Article 116
31 Jul 2026	IRS assessment target	AT should issue assessments for timely-filed returns by this point	Taxpayers who filed on time	Check Portal das Finanças if nothing appears by early August
31 Aug 2026	IRS refund or payment deadline	Receive refund or pay tax owed using the reference in the nota de liquidação	Timely filed IRS returns	Interest and enforcement risk after the deadline
Jul 2026	Recibos verdes quarterly declaration	Submit declaração trimestral (Q2)	Self-employed workers	Fine and contribution correction risk
Aug 2026	IMI second instalment	Pay second IMI instalment if your bill is above €500	Property owners with bills split into three instalments	Interest and enforcement risk
Sep 2026	AIMI payment	Pay AIMI if threshold is exceeded	Property owners above AIMI threshold	Enforcement risk
Oct 2026	Recibos verdes quarterly declaration	Submit declaração trimestral (Q3)	Self-employed workers	Fine and contribution correction risk
Nov 2026	IMI later instalments	Pay second instalment for €100–€500 bills or third instalment for bills above €500	Property owners with bills split across instalments	Interest and enforcement risk
Vehicle reg. month	IUC vehicle tax	Pay via Portal das Finanças	Vehicle owners	Fine and possible enforcement action
By 20th of each month	Segurança Social contributions	Pay monthly contribution	Self-employed workers and other contributors	Interest and contribution debt