Must / Need to / Should / May
UsageUse must for obligations, need to for necessary process steps, should for recommendations and may for permission or options.
Must
Use when
A requirement is mandatory and failure to comply has a consequence.
Example
“Applicants must submit proof of identity.”
Need to
Use when
A step is practically necessary to complete a task or process.
Example
“You need to create an account before saving a draft.”
Should
Use when
You are making a recommendation rather than imposing a requirement.
Example
“Teams should review access permissions every quarter.”
May
Use when
An action is permitted, possible or optional.
Example
“Applicants may attach supporting documents.”
Quick check
should as a requirement, may as an obligation, must for an optional step
Usage note
In legislation, contracts and regulated policies, modal verbs may have defined legal effects. Follow the governing drafting standard.