Legal Dirhams from Shahjahanabad mint are almost always found in round shape. This coin is square.

Legal Dirham or Dirham Shara'ai - Obv: Farsi inscription Dirham Shara'ai with AH date & RY. Rev: Mint-name. Usually these strange coins are found with square flans. Only the coins from Akbarabad and Shahjahanabad are known in round flans. Under Islamic Law, the Jizya جزية is a per capita tax levied on a section of the non-Muslim subjects of an Islamic state. The tax is to be levied on able-bodied adult males of military age (but with specific exemptions). Jizya was a material proof of the non-Muslims' acceptance of subjection to the state and its laws. In return, non-Muslim subjects are permitted to practice their faith, to enjoy a measure of communal autonomy, to be entitled to the Muslim state's protection from outside aggression, and to be exempted from military servuce and from the ‘Zakat’ tax levied upon Muslim citizens. The Arabic term jizya appears in 29th verse of the 9th Chapter named ‘al-Tawbah’ or “repentance” (Qura’an 9:29) - “Fight those who do not believe in Allah or in the Last Day and who do not consider unlawful what Allah and His Messenger have made unlawful and who do not adopt the religion of truth from those who were given the Scripture - [fight] until they give the jizyah willingly while they are humbled.” Persons who paid the tax were divided into three classes – the Poor, the Middle Classes and the Rich. The rates were 12, 24 and 48 Dirhams respectively. But as there was no Dirham current in India, un-coined silver was to be taken – from the first class (the Poors) 3 Tolchas 1 4/5 Masha, double that from the next class and four times that from the Rich. If Rupees were collected they were received in equal weights to the corresponding amount of silver specified. Collection was made from the Rich in four installments per year, from the Middle Classes in two and from the Poor once a year. There were a range of exemptions and amendments prescribed for various situations. Special coins called Dirham Shara’ee were struck to alleviate this complication brought about by the non-prevalence of the Dirham in India. As this coin weighs around 3 gm, it is roughly equal to about 3 Annas 8 pies. Going by the prescribed amounts, the tax for the Poor will be 2 Rupees 12 Annas, for the Middle Classes 5 Rupees 8 Annas and for the Rich 11 Rupees per annuum. This amount is actually lesser than the amount they would pay if they paid the tax as un-coined silver. The tax was abolished by Akbar but revived by Aurangzeb in his 22nd RY, AH1090 (12 April 1679).