Quick background, I'm a physician in a multi-physician practice owned by a major practice management company. I have a salaried position + production bonus that comes in as W2 income. My wife and I are having difficulty with getting pregnant and so are starting infertility treatments.
In order to pay for said treatments, I will be picking up some extra shifts at a different hospital (locum tenens) that will be 1099 income. Because it's going to a specific use, I need to maximize the cash flow in the immediate short term - so not looking to put any money in any tax sheltered accounts.
Having a hard time figuring out however what amount I should be keeping aside for taxes? Online tools I've seen don't seem to handle the W2 income very well. Just save something equal to what will be my marginal rate? More? Less? Set up a pass through (is this even an option if I also have W2 income?)?
I obviously don't want to run afoul of the IRS and pay the estimated taxes on time, but really want to have maximal availability of funds in case things get really expensive.