Wrong basic salary in income tax return

A user mistakenly entered their net salary instead of basic salary on their income tax return, leading to a notice regarding HRA claims. Despite informing the tax authorities, a demand was raised. The user is seeking advice on how to resolve this, especially since the return is for AY 20-21 and cannot be revised online. Suggestions include visiting the Assessing Officer (AO) or using the AO office correspondence feature on the PAN portal to respond to the notice.