QUESTION
Service Provider liable to register on 1st Mar 18. Service Provider apply for registration on 14th Dec 19 (after the expiry of 30 days from the date of his becoming liable to registration). What is the effective date of registration? How service provider pay the liability for the year 2017-18? Can he able to file the previous return with payment of tax?

ANSWER
Facts of the case:
Service provider liable to be registered on 1st March 2018, however applies for registration on 14th December 2019.

Law applicable:
CGST RULE 10
(3) Where an application for registration has been submitted by the applicant after the expiry of thirty days from the date of his becoming liable to registration, the effective date of registration shall be the date of the grant of registration under sub-rule (1) or sub-rule (3) or sub-rule (5) of rule 9.

SECTION 40 OF CGST ACT
Every registered person who has made outward supplies in the period between the date on which he became liable to registration till the date on which registration has been granted shall declare the same in the first return furnished by him after grant of registration.

Interpretation: Effective date of registration shall be the date of grant of registration and as per section 40 supplier is required to declare all the outward supplies from the date he becomes liable for registration till registration has been granted in the first return to be filed after grant of registration.
Accordingly, the supplier is liable to pay tax along with interest for all the supplies made from 1st March 2018 till the date of grant of registration.

Conclusion: You are required to declare and pay tax along with interest for all the supplies made from 1st March 2018 till the date of grant of registration in the first return to be filed after grant of registration.