For a Singapore company limited by shares, the general ACRA minimum is S$1 in share capital. This should not be confused with paid-up capital: shares may be issued without being fully paid, so issued share capital and paid-up share capital are not necessarily the same amount.
Certain regulated activities, licences, work-pass applications, banking arrangements or commercial contracts may require or make it practical to maintain a higher capital level. Those are industry, licensing or commercial requirements, not the general Companies Act incorporation minimum.