What are the Sharia-compliant types of fixed income, and are coupon bonds and inflation-protected treasury bonds consistent with them?

Allah has permitted trade and forbidden usury (riba). Therefore, every earning that is free from usury, the sale of prohibited items, gharar (excessive uncertainty), or injustice is permissible. The general rule for all types of trade is permissibility, unless they involve consuming people's wealth unlawfully. This includes usury and gambling, because a usurer acquires money without effort.

There is no contract in Islamic law that allows a person to pay money to another to receive it back after a period with a guaranteed profit. This is forbidden by the consensus of scholars. Examples include:

1. Investment in bonds of all types, which means the investor pays an amount in exchange for its return with a stipulated interest or benefit, such as zero-coupon bonds and inflation-protected bonds. All of these are forms of usury.

2. The Islamic Fiqh Council has affirmed that bonds representing a commitment to pay their amount with a stipulated interest or benefit are religiously prohibited, whether in terms of issuance, purchase, or trading, because they are usurious loans.

3. Zero-coupon bonds and prize bonds are also forbidden.

4. The Islamic alternative is bonds or sukuk based on the principle of Mudarabah (profit-sharing) for a specific project or investment activity, whereby their owners do not receive a fixed interest or benefit, but rather a percentage of the project's profit if it materializes.