SG41300 - Requirement to give security: VAT and environmental taxes: requiring security and directing a person to make monthly returns
In some cases the risk to the revenue might be such that you require the person to give security and to make monthly returns.
The Notice of Requirement (NOR) can be adapted to show the amount of security you require as being the lower amount based upon the person making monthly returns.
At the same time that you serve the NOR you should serve a Notice of Direction (NOD) directing the person to make monthly returns, see SG25540.