Hello,
Congratulations on your new job and emerging business. You are correct to be concerned and want to account for these changes. I am going to include a refund estimator link so you can see how these items will affect your taxes and minimize any deficiencies at the end of the year. I will also include an article about the w4 form and w4 calculator. Those tools will assist you in completing the w4 form correctly for your new employer and minimize withholding shortages.
https://turbotax.intuit.com/lp/ppc/2541?srqs=null&cid=ppc_gg_nb_stan_all_na_Calculator-CalculatorEst...
https://turbotax.intuit.com/tax-tools/calculators/w4/
https://turbotax.intuit.com/tax-tips/irs-tax-forms/what-is-a-w-4-form/L2NapDzX2
https://turbotax.intuit.com/tax-tips/irs-tax-forms/how-to-estimate-federal-withholding/L99CO0yTK
