Salam; I live in Canada and i have been charged an interest for filing my business tax late (due to the accountant) even though i paid it on the due date but Revenue Canada (Tax Ministry) received the amount late. I always avoid interest but this is what happened and i don't know what to do. Have i fall in Riba

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

You bear no sin for such penalties and interest imposed on late payment of tax due to the accountant’s mistake or for paying such interest if there was no way to get such late payment penalties waived. In fact, you should explain to the concerned authority that it was not your fault and that you did not delay the payment of the tax; instead, it was the accountant’s fault.

If they do not take that factor into consideration and obliged you to pay this interest and you cannot find any way to avoid it, you should pay it. A Muslim should not degrade himself by placing himself in difficult situations he cannot handle. The Prophet, sallallaahu ‘alayhi wa sallam, said: “A believer should not degrade himself.” The Companions asked, “How does he humiliate himself?” The Prophet, sallallaahu ‘alayhi wa sallam, said: “By taking on a trial that he cannot deal with.” [At-Tirmithi and others - Al-Albaani graded it as Saheeh (sound)]

Allaah Knows best.