The proper officer, in relation to assessment of taxes on the unregistered taxable person, shall issue the assessment order in FORM GST ASMT-15 within 5 years from the date specified under Section 44 for furnishing of the annual return for the financial year to which the tax not paid relates.
(ICAI FAQ PUBLICATIONS 06-09-2017 ASSESSMENT OF UNREGISTERED PERSONS: FAQ NO. 21)