EContas outlines the key tax and reporting obligations due in January so businesses and households stay compliant with the Tax and Customs Authority (AT) and Social Security (SS). Important January items include the Day 9 electronic communications for IRS (personal income tax), IRC (corporation tax) and VAT, SAF‑T invoicing requirements, VAT returns and payments, and related Social Security filings — all with strict deadlines and penalties for late or incorrect submissions. Use the EContas checklist to prioritise filings, confirm filing channels (electronic transmission), and avoid sanctions.