rule 4 of companies (share capital and debenture) rule 2014

Shares with differential rights shall not exceed at any point of time more than 26% of its paid up capital + any equity shares previously issued with differential voting right ,it's a maximum ceiling.
For example ,if company have total paid up equity of 1000₹ and would like to issue further 25 shares at ₹10 with differential rights of voting / dividend ,then post issue capital is ₹1250 and part of differential voting rights is (25*10)/1250=20% ,So Max 26%