What happens if the taxable person files the return
but does not make payment of tax?

In such cases, the return is not considered as a valid
return. Section 2(117) defines a valid return to mean a
return furnished under sub-section (1) of section 39 on which self-assessed tax has been paid in full. It is only the valid return that would be used for allowing input tax credit (ITC) to the recipient. In other words, unless the supplier has paid the entire self-assessed tax and filed his return and the recipient has filed his return, the ITC of the recipient would not be confirmed.

Recommendation of 48th gst council👆

Does cancellation of registration impose any
tax obligations on the person whose registration is
so cancelled?

Yes, as per Section 29(5) of the CGST/SGST Act, every
registered taxable person whose registration is cancelled shall pay an amount, by way of debit in the electronic cash/credit ledger, equivalent to the credit of input tax in respect of inputs held in stock and inputs contained in semi-finished or finished goods held in stock or capital goods or plant and machinery on the day immediately preceding the
date of such cancellation or the output tax payable on such goods, whichever is higher.

Income Tax exemption limit: Good news for taxpayers! Up to ₹ 5 lakh can be exempted in income tax
https://www.rightsofemployees.com/income-tax-exemption-limit-good-news-for-taxpayers-up-to-%E2%82%B9-5-lakh-can-be-exempted-in-income-tax/