Section 22 of CSGT act deals with “Persons liable for registration” and section 24 deals with “Compulsory registration in certain cases”.
Section 22 of the Central Goods and Services Act, 2017 (CGST Act)
Persons liable for registration
(1) Every supplier shall be liable to be registered under this Act in the State or Union territory, other than special category States, from where he makes a taxable supply of goods or services or both, if his aggregate turnover in a financial year exceeds twenty lakh rupees: Provided that where such person makes taxable supplies of goods or services or both from any of the special category States, he shall be liable to be registered if his aggregate turnover in a financial year exceeds ten lakh rupees.
(2) Every person who, on the day immediately preceding the appointed day, is registered or holds a licence under an existing law, shall be liable to be registered under this Act with effect from the appointed day.
(3) Where a business carried on by a taxable person registered under this Act is transferred, whether on account of succession or otherwise, to another person as a going concern, the transferee or the successor, as the case may be, shall be liable to be registered with effect from the date of such transfer or succession.
(4) Notwithstanding anything contained in sub-sections (1) and (3), in a case of transfer pursuant to sanction of a scheme or an arrangement for amalgamation or, as the case may be, demerger of two or more companies pursuant to an order of a High Court, Tribunal or otherwise, the transferee shall be liable to be registered, with effect from the date on which the Registrar of Companies issues a certificate of incorporation giving effect to such order of the High Court or Tribunal. Explanation.––For the purposes of this section,––

(i) the expression “aggregate turnover” shall include all supplies made by the taxable person, whether on his own account or made on behalf of all his principals;
(ii) the supply of goods, after completion of job work, by a registered job worker shall be treated as the supply of goods by the principal referred to in section 143, and the value of such goods shall not be included in the aggregate turnover of the registered job worker;
(iii) the expression “special category States” shall mean the States as specified in sub-clause (g) of clause (4) of article 279A of the Constitution.

Section 24 – Compulsory registration in certain cases.2
Notwithstanding anything contained in sub-section (1) of section 22, the following categories of persons shall be required to be registered under this Act,––

(i) persons making any inter-State taxable supply;3
(ii) casual taxable persons making taxable supply;
(iii) persons who are required to pay tax under reverse charge;
(iv) person who are required to pay tax under sub-section (5) of section 9;
(v) non-resident taxable persons making taxable supply;
(vi) persons who are required to deduct tax under section 51, whether or not separately registered under this Act;
(vii) 4persons who make taxable supply of goods or services or both on behalf of other taxable persons whether as an agent or otherwise;
(viii) Input Service Distributor, whether or not separately registered under this Act;
(ix) persons who supply goods or services or both, other than supplies specified under sub-section (5) of section 9, through such electronic commerce operator who is required to collect tax at source under section 52;
(x) every electronic commerce operator who is required to collect tax at source under section 52;5
(xi) every person supplying online information and database access or retrieval services from a place outside India to a person in India, other than a registered person; and
(xii) such other person or class of persons as may be notified by the Government on the recommendations of the Council.6

Now coming to your question, if you are covered in above section and liable for GST registration then you have to apply for registration as soon as possible but if you are not covered and not liable for GST registration then you need not apply for registration.
AND if you are not registrered and not covered and not liable for registration THEN if any detail was sought by department then you should provide the detail so that department also satisfies that you are not liable for registration. But if you do not provide information then department will suspect that you are hiding the detail and not taking registration even after being liable.
As per section 122 of the CGST Act, a person/supplier exceeds the threshold limit for GST registration and becomes taxable or is legally bound to get registered, and if a person has failed to obtain the registration the penalty is equivalent to: penalty for nonregistration under GST shall be INR 10,000/- (ten thousand rupees) or an amount equivalent to the tax evaded, whichever is higher
You may have to face consequences like:-

1. Detention of goods and vehicles.
2. Confiscation of goods and vehicles.
3. The person/supplier cannot claim the ITC.
4. The person/supplier cannot transfer the input tax credit.
5. The penalty of INR 10,000/- or an amount equivalent to the tax evaded whichever is higher.

Section 22 of CSGT act deals with “Persons liable for registration” and section 24 deals with “Compulsory registration in certain cases”.
Section 22 of the Central Goods and Services Act, 2017 (CGST Act)
Persons liable for registration
(1) Every supplier shall be liable to be registered under this Act in the State or Union territory, other than special category States, from where he makes a taxable supply of goods or services or both, if his aggregate turnover in a financial year exceeds twenty lakh rupees: Provided that where such person makes taxable supplies of goods or services or both from any of the special category States, he shall be liable to be registered if his aggregate turnover in a financial year exceeds ten lakh rupees.
(2) Every person who, on the day immediately preceding the appointed day, is registered or holds a licence under an existing law, shall be liable to be registered under this Act with effect from the appointed day.
(3) Where a business carried on by a taxable person registered under this Act is transferred, whether on account of succession or otherwise, to another person as a going concern, the transferee or the successor, as the case may be, shall be liable to be registered with effect from the date of such transfer or succession.
(4) Notwithstanding anything contained in sub-sections (1) and (3), in a case of transfer pursuant to sanction of a scheme or an arrangement for amalgamation or, as the case may be, demerger of two or more companies pursuant to an order of a High Court, Tribunal or otherwise, the transferee shall be liable to be registered, with effect from the date on which the Registrar of Companies issues a certificate of incorporation giving effect to such order of the High Court or Tribunal. Explanation.––For the purposes of this section,––

(i) the expression “aggregate turnover” shall include all supplies made by the taxable person, whether on his own account or made on behalf of all his principals;
(ii) the supply of goods, after completion of job work, by a registered job worker shall be treated as the supply of goods by the principal referred to in section 143, and the value of such goods shall not be included in the aggregate turnover of the registered job worker;
(iii) the expression “special category States” shall mean the States as specified in sub-clause (g) of clause (4) of article 279A of the Constitution.

Section 24 – Compulsory registration in certain cases.
Notwithstanding anything contained in sub-section (1) of section 22, the following categories of persons shall be required to be registered under this Act,––

(i) persons making any inter-State taxable supply;
(ii) casual taxable persons making taxable supply;
(iii) persons who are required to pay tax under reverse charge;
(iv) person who are required to pay tax under sub-section (5) of section 9;
(v) non-resident taxable persons making taxable supply;
(vi) persons who are required to deduct tax under section 51, whether or not separately registered under this Act;
(vii) persons who make taxable supply of goods or services or both on behalf of other taxable persons whether as an agent or otherwise;
(viii) Input Service Distributor, whether or not separately registered under this Act;
(ix) persons who supply goods or services or both, other than supplies specified under sub-section (5) of section 9, through such electronic commerce operator who is required to collect tax at source under section 52;
(x) every electronic commerce operator who is required to collect tax at source under section 52;
(xi) every person supplying online information and database access or retrieval services from a place outside India to a person in India, other than a registered person; and
(xii) such other person or class of persons as may be notified by the Government on the recommendations of the Council.

Now coming to your question, if you are covered in above section and liable for GST registration then you have to apply for registration as soon as possible but if you are not covered and not liable for GST registration then you need not apply for registration.
AND if you are not registrered and not covered and not liable for registration THEN if any detail was sought by department then you should provide the detail so that department also satisfies that you are not liable for registration. But if you do not provide information then department will suspect that you are hiding the detail and not taking registration even after being liable.
As per section 122 of the CGST Act, a person/supplier exceeds the threshold limit for GST registration and becomes taxable or is legally bound to get registered, and if a person has failed to obtain the registration the penalty is equivalent to: penalty for nonregistration under GST shall be INR 10,000/- (ten thousand rupees) or an amount equivalent to the tax evaded, whichever is higher
You may have to face consequences like:-

1. Detention of goods and vehicles.
2. Confiscation of goods and vehicles.
3. The person/supplier cannot claim the ITC.
4. The person/supplier cannot transfer the input tax credit.
5. The penalty of INR 10,000/- or an amount equivalent to the tax evaded whichever is higher.

Section 22 of CSGT act deals with “Persons liable for registration” and section 24 deals with “Compulsory registration in certain cases”.
Section 22 of the Central Goods and Services Act, 2017 (CGST Act)
Persons liable for registration
(1) Every supplier shall be liable to be registered under this Act in the State or Union territory, other than special category States, from where he makes a taxable supply of goods or services or both, if his aggregate turnover in a financial year exceeds twenty lakh rupees: Provided that where such person makes taxable supplies of goods or services or both from any of the special category States, he shall be liable to be registered if his aggregate turnover in a financial year exceeds ten lakh rupees.
(2) Every person who, on the day immediately preceding the appointed day, is registered or holds a licence under an existing law, shall be liable to be registered under this Act with effect from the appointed day.
(3) Where a business carried on by a taxable person registered under this Act is transferred, whether on account of succession or otherwise, to another person as a going concern, the transferee or the successor, as the case may be, shall be liable to be registered with effect from the date of such transfer or succession.
(4) Notwithstanding anything contained in sub-sections (1) and (3), in a case of transfer pursuant to sanction of a scheme or an arrangement for amalgamation or, as the case may be, demerger of two or more companies pursuant to an order of a High Court, Tribunal or otherwise, the transferee shall be liable to be registered, with effect from the date on which the Registrar of Companies issues a certificate of incorporation giving effect to such order of the High Court or Tribunal. Explanation.––For the purposes of this section,––
(i) the expression “aggregate turnover” shall include all supplies made by the taxable person, whether on his own account or made on behalf of all his principals;
(ii) the supply of goods, after completion of job work, by a registered job worker shall be treated as the supply of goods by the principal referred to in section 143, and the value of such goods shall not be included in the aggregate turnover of the registered job worker;
(iii) the expression “special category States” shall mean the States as specified in sub-clause (g) of clause (4) of article 279A of the Constitution.
Section 24 – Compulsory registration in certain cases.
Notwithstanding anything contained in sub-section (1) of section 22, the following categories of persons shall be required to be registered under this Act,––
(i) persons making any inter-State taxable supply;
(ii) casual taxable persons making taxable supply;
(iii) persons who are required to pay tax under reverse charge;
(iv) person who are required to pay tax under sub-section (5) of section 9;
(v) non-resident taxable persons making taxable supply;
(vi) persons who are required to deduct tax under section 51, whether or not separately registered under this Act;
(vii) persons who make taxable supply of goods or services or both on behalf of other taxable persons whether as an agent or otherwise;
(viii) Input Service Distributor, whether or not separately registered under this Act;
(ix) persons who supply goods or services or both, other than supplies specified under sub-section (5) of section 9, through such electronic commerce operator who is required to collect tax at source under section 52;
(x) every electronic commerce operator who is required to collect tax at source under section 52;
(xi) every person supplying online information and database access or retrieval services from a place outside India to a person in India, other than a registered person; and
(xii) such other person or class of persons as may be notified by the Government on the recommendations of the Council.
Now coming to your question, if you are covered in above section and liable for GST registration then you have to apply for registration as soon as possible but if you are not covered and not liable for GST registration then you need not apply for registration.
AND if you are not registrered and not covered and not liable for registration THEN if any detail was sought by department then you should provide the detail so that department also satisfies that you are not liable for registration. But if you do not provide information then department will suspect that you are hiding the detail and not taking registration even after being liable.
As per section 122 of the CGST Act, a person/supplier exceeds the threshold limit for GST registration and becomes taxable or is legally bound to get registered, and if a person has failed to obtain the registration the penalty is equivalent to: penalty for nonregistration under GST shall be INR 10,000/- (ten thousand rupees) or an amount equivalent to the tax evaded, whichever is higher
You may have to face consequences like:-

1. Detention of goods and vehicles.
2. Confiscation of goods and vehicles.
3. The person/supplier cannot claim the ITC.
4. The person/supplier cannot transfer the input tax credit.
5. The penalty of INR 10,000/- or an amount equivalent to the tax evaded whichever is higher.

Section 22 of CSGT act deals with “Persons liable for registration” and section 24 deals with “Compulsory registration in certain cases”.
Coming to your question, if you are covered in above section and liable for GST registration then you have to apply for registration as soon as possible but if you are not covered and not liable for GST registration then you need not apply for registration. 
AND if you are not registrered and not covered and not liable for registration THEN if any detail was sought by department then you should provide the detail so that department also satisfies that you are not liable for registration. But if you do not provide information then department will suspect that you are hiding the detail and not taking registration even after being liable.
 As per section 122 of the CGST Act, a person/supplier exceeds the threshold limit for GST registration and becomes taxable or is legally bound to get registered, and if a person has failed to obtain the registration the penalty is equivalent to: penalty for nonregistration under GST shall be INR 10,000/- (ten thousand rupees) or an amount equivalent to the tax evaded, whichever is higher
You may have to face consequences like:-

1. Detention of goods and vehicles.
2. Confiscation of goods and vehicles.
3. The person/supplier cannot claim the ITC.
4. The person/supplier cannot transfer the input tax credit.
5. The penalty of INR 10,000/- or an amount equivalent to the tax evaded whichever is higher.

Section 22 of the Central Goods and Services Act, 2017 (CGST Act)
Persons liable for registration
(1) Every supplier shall be liable to be registered under this Act in the State or Union territory, other than special category States, from where he makes a taxable supply of goods or services or both, if his aggregate turnover in a financial year exceeds twenty lakh rupees: Provided that where such person makes taxable supplies of goods or services or both from any of the special category States, he shall be liable to be registered if his aggregate turnover in a financial year exceeds ten lakh rupees.
(2) Every person who, on the day immediately preceding the appointed day, is registered or holds a licence under an existing law, shall be liable to be registered under this Act with effect from the appointed day.
(3) Where a business carried on by a taxable person registered under this Act is transferred, whether on account of succession or otherwise, to another person as a going concern, the transferee or the successor, as the case may be, shall be liable to be registered with effect from the date of such transfer or succession.
(4) Notwithstanding anything contained in sub-sections (1) and (3), in a case of transfer pursuant to sanction of a scheme or an arrangement for amalgamation or, as the case may be, demerger of two or more companies pursuant to an order of a High Court, Tribunal or otherwise, the transferee shall be liable to be registered, with effect from the date on which the Registrar of Companies issues a certificate of incorporation giving effect to such order of the High Court or Tribunal. Explanation.––For the purposes of this section,––
(i) the expression “aggregate turnover” shall include all supplies made by the taxable person, whether on his own account or made on behalf of all his principals;
(ii) the supply of goods, after completion of job work, by a registered job worker shall be treated as the supply of goods by the principal referred to in section 143, and the value of such goods shall not be included in the aggregate turnover of the registered job worker;
(iii) the expression “special category States” shall mean the States as specified in sub-clause (g) of clause (4) of article 279A of the Constitution.

Section 24 – Compulsory registration in certain cases.
Notwithstanding anything contained in sub-section (1) of section 22, the following categories of persons shall be required to be registered under this Act,––
(i) persons making any inter-State taxable supply;
(ii) casual taxable persons making taxable supply;
(iii) persons who are required to pay tax under reverse charge;
(iv) person who are required to pay tax under sub-section (5) of section 9;
(v) non-resident taxable persons making taxable supply;
(vi) persons who are required to deduct tax under section 51, whether or not separately registered under this Act;
(vii) persons who make taxable supply of goods or services or both on behalf of other taxable persons whether as an agent or otherwise;
(viii) Input Service Distributor, whether or not separately registered under this Act;
(ix) persons who supply goods or services or both, other than supplies specified under sub-section (5) of section 9, through such electronic commerce operator who is required to collect tax at source under section 52;
(x) every electronic commerce operator who is required to collect tax at source under section 52;
(xi) every person supplying online information and database access or retrieval services from a place outside India to a person in India, other than a registered person; and
(xii) such other person or class of persons as may be notified by the Government on the recommendations of the Council.