Husband refusing to tell his wife how much he owns

A man is not obliged to tell his wife what he
has in the bank, just as she is not obliged to tell him what she owns of her own personal wealth. 

But the loving relationship that should exist
between husband and wife implies that they should be easy-going in this matter, and that each should let the other know what he or she has, and
they should cooperate in organizing their finances and spending in ways that please Allaah. 

And Allaah knows best.