Advance tax - issue letters from ito

In past one month, 2 senior citizens have received Advance Tax-Issue letter from their ITO by email, asking them to pay advance tax for Ay 19-20.

As you know Senior citizens without business income are not required to pay advance tax. They have been paying full tax on self assessment in past years, and were not charged any interest.

So why these issue letters are coming now ?? Is the law changed for senior citizens advance tax? Is anyone else facing this problem with their clients?