I Gave Her A Budget To Stay Under

When she goes over it and apologizes with sex, will do whatever I want and sometimes I put some spanking in there just so she is not enjoying it completely or maybe she is.
Few weekends ago she went out shopping with a friend, came home with a dozen bags or more, I was downstairs a bit later watching TV and she came down naked and just bent over in front of me saying she was bad. I just spanked her and had her suck on me then spanked her again giving her no sexual gratification at all, seriously think she gets off on this now.
Truth is the budget I gave her is like a third of what I want to stay under every month, she has no idea what my salary is let alone what is already saved for retirement, house is paid off along with our vehicles. I think she just likes the little punishments.