Bank transfer

There is no problem in gifting any amount to your wife. You have said that both of you earn salary and I hope your taxes are deducted at source and you file returns regularly. You are just transferring your taxed income to her.

But in the event she invests this amount, the clubbing provisions might get attracted. The interest she earns on (for eg) the FDs made by her out of this amount would be taxed as your income. (As per your query she spends the whole amount, so no issues abt that too!)

As you said that you transfer the some amount every month for house hold exp. etc and if she can prove that  those transfers has been spent as drawings and house hold expenses than clubbing of income provision will be not attracted.

in that case no need to worry