Self-employed: the second IRS advance payment is due by 20 September

People with self-employed or business income (category B) make IRS advance payments — pagamentos por conta — in three instalments: by 20 July, 20 September and 20 December. The tax authority notifies you in the month before each deadline, and the amount is based on the tax assessment for the year before last. When the final IRS bill is settled, the advance payments are credited: if you paid more than the tax due, the difference is refunded; if less, you pay the rest.