Paying No UK Tax on Interest/Capital Gains

Currently my wife takes care of our child (soon to be children) full-time and does not work.  Because of this her UK personal allowance and lower tax brackets are "lost".  I am in the process of moving all our savings accounts and investments into her name, thus avoiding the 40% tax bracket and paying zero tax to the UK (US would hit me up for their slice though, but at least that protects me from AMT).

Is there anything wrong with this, my earnings going straight into her savings to avoid tax liability?

I am guessing you are resident in the UK.

You don't say what nationality you are nor what nationality your wife is.  This may affect the situation.

The issue here would be a potential liability for gift tax (US) and/or inheritance tax (UK & US).  The details depend on your nationalities and your domicile status.