There are a few checkpoints that one has to keep track of before 31.3.2021.Let me specify top 17 among them:

• If deduction u/s 80 is to be claimed in income tax, then every taxpayer should verify the limits of income tax and their tax liability and should invest, donate, etc. before 31st March.
  
• Income tax follows the principle of “Pay As You Earn”.So you must calculate your advance tax liability and pay it quarterly to avoid unnecessary interest.It is also necessary that the advance tax paid should get credited to the account of central govt. before 31st March 2021 and you should receive the challan serial number along with date of 31st March 2021 or before. A mere deposit before 31st March 2021 is not sufficient.
  
• Salaried Employee should give the details of Investments and deductions to Employer so that less TDS will be deducted in March month.
  
• Take a physical inventory of Raw Materials, Work In Progress, Finished Good, Stores & Spares, Loose Tools, Consumables etc as on 31st March,2021.
  
• One should download 26AS and reconcile the income and tax deducted thereon as per books and as per 26AS.If any rectification is needed,the same should follow up.
• Deadline to file the belated ITR for FY 2019-20 is 31st March, 2021. Also, late fees for Belated Return is Rs.10,000.
  
• TDS on all expenses for the period 2020-21 should be done and paid else 30% of such expenditure will be disallowed.
  
• Aadhaar-PAN linking is now mandatory for the PAN holders requiring filing of Income Tax Return. The last date to link aadhaar number and PAN is 31.03.2021.
  
• Try to purchase assets before 31.3.2021 ,if needed to claim depreciation as expense during FY 2020-21 .
• To manage capital gain on Securities,one can calculate their gains and book respective amount to losses to reduce their tax liability.Further same asset can be purchased again if needed.
• Do take a note of your unabsorbed losses.If it is the expiry year for the same and you have scope of gain booking,then do it to absorb the losses.
• Verify loan accounts and cleanup them up if necessary. If an assessee has given or taken any temporary loans, hand loans and are outstanding, try to repay / recover the same on or before 31st March 2021. This will help in improving the balance sheet position of the ratio of assets and liabilities, Debt Equity Ratio etc.
  
• Businesses which are not yet under the GST registration limit of Rs.20 lakh, should keep track of their turnover. The total turnover up to 31st March is to be calculated for the purpose of determining the important aspects like applicability of GST Registration and returns.
  
• The taxpayers should reconcile the Cash Ledger, Credit Ledger and Liability Ledger on GSTN portal with their books of accounts. All the entries should be done before the year-end. Further, debit notes, credit notes, rate difference, discount, etc also should to be reconciled.
  
• All the exporters who make exports without paying tax under LUT should apply for LUT for FY 21-22.
  
• Credit Notes/ Debit notes if any should be issued before 30th September 2021 in relation to invoices issued during the year 20-21.
  
•  New billing series for FY 21-22 w.e.f 1st April 2021.