Applied for an ex officio review? Compensatory interest only runs one year after the request, rules the Supreme Administrative Court
The full bench of the Tax Litigation Section of the Supreme Administrative Court has settled the case law: where a taxpayer recovers tax through an ex officio review request (article 78 of the General Tax Law), compensatory interest is due only once a year has elapsed from the filing of the request — not from the undue payment — whether the annulment comes through administrative or judicial channels, unless the delay is not attributable to the Tax Authority (article 43(3)(c) of the General Tax Law). The case arose from litigation over vehicle tax (ISV) on imported used cars, but its reach extends to all taxes. The practical lesson: reacting within the deadlines for administrative claims or judicial challenges preserves interest from the date of payment; letting the deadline pass and later resorting to ex officio review costs at least a year of interest. Ref.: Supreme Administrative Court Judgment no. 18/2026 (full Tax Litigation Section), Official Gazette no. 149/2026, 1st series, 04/08/2026.
Vehicle tax overhaul: payment on fixed dates from 2027 — in 2026 everything stays the same
Decree-Law no. 161/2026 of 4 August reforms IUC payment: from 01/01/2027, the tax will be assessed annually, centrally and per taxpayer, covering all vehicles registered on 1 January, with payment along IMI lines — a single instalment in April up to €100, April and October between €100 and €500, and April, July and October above €500. A transitional regime applies in 2027 (October, or July and October) and missing one instalment makes the rest immediately due; the exemption for persons with disabilities is capped at one vehicle and €240 per year. In 2026 nothing changes: payment remains due in the month of the registration anniversary, as always. Companies with fleets and households with several vehicles should prepare for the concentration of payments. Ref.: Decree-Law no. 161/2026, Official Gazette no. 149/2026, 1st series, 04/08/2026 (effects from 01/01/2027).
Tax Authority clarifies loyalty discounts, self-billing and US LLCs; CAAD tightens RFAI again
In early August the Tax Authority released a batch of binding rulings with practical relevance: in VAT, the treatment of loyalty discounts used across successive purchases at different rates (ruling 30283), the evidentiary requirements for self-billing and credit-note adjustments, including the limits of tacit-acceptance clauses (ruling 30339), and tourist packages combining own and third-party services (ruling 30315). On the international front, ruling 30630 clarifies the taxation of income paid to a fiscally transparent US LLC, attributed to its member (Portugal-US tax treaty). At the CAAD arbitration court, the decision in case no. 802/2025-T (19/05/2026) again demands effective proof of the relevant investment and of job creation under the RFAI incentive. Companies running loyalty schemes, self-billing or RFAI benefits should review procedures and evidence files. Ref.: Binding rulings nos. 30283, 30339 and 30315 (orders of 27-29/07/2026) and 30630 (order of 26/07/2026), Tax Authority; CAAD, case no. 802/2025-T.
Tax calendar: September brings double VAT and payments on account
After the August pause, September concentrates obligations: by 07/09, invoice reporting (SAF-T) for August; by 10/09, the August payroll declaration (DMR); by 21/09, IRS/IRC withholding tax and Stamp Duty, the 2nd IRS payment on account (category B), the EU recapitulative statement and — the effect of August’s flexibilisation — the periodic VAT returns for the monthly regime covering June and July, plus the quarterly return for Q2; by 25/09, payment of the corresponding VAT. By 30/09: the 2nd IRC payment on account, the 2nd additional payment on account of the State surtax, AIMI and the IUC for vehicles registered in September. Dates confirmed in the Tax Authority’s official calendar — plan September’s cash flow ahead. Ref.: Tax Authority, 2026 Tax Agenda — Reporting and Payment Obligations (June 2026 update).
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