Quarterly IRS Payments — Pagamentos por Conta

Quarterly advance tax payments (pagamentos por conta) are required for self-employed (Category B) taxpayers whose income is not subject to withholding at source. They are due three times per year: 31 July, 30 September, and 31 December. The amount for each installment is calculated by AT based on the IRS paid in the previous year. New taxpayers in their first year of Cat. B income are generally exempt from quarterly payments. The quarterly payments are credited against the final IRS liability when the Modelo 3 is filed. If the payments are insufficient, the balance is due upon filing; if excess, a refund is issued. Taxpayers can reduce quarterly payments if they anticipate lower income in the current year, but must provide justification.