Step 1: Recall Companies Act rules.
According to the Companies (Share Capital and Debenture) Rules, 2014, companies issuing debentures must create a Debenture Redemption Reserve (DRR).
Step 2: Required percentage.
The law requires companies to transfer at least 25% of the value of debentures issued into the DRR before redemption begins.
Step 3: Conclude.
Thus, the percentage is 25%.
Final Answer:
\[
\boxed{25%}
\]