Visitor visa - Retired no tax returns

[rubies]

Hi,

My parents are attending visitor visa interview in a few days. Dad is aged above 70 years, retired and receiving pension. Is he required to have tax returns filed? Also he owns the house in which my parents live in our home town and pays house tax regularly. He is taking his property papers and also mentioned in his affidavit about the house and its approximate value. Should he carry any papers to show that he is paying house tax?

[immihelp]

If he does not make enough money to be required to file income tax returns, he does not have to show them.