Anatomy of a Paycheck
How federal
income tax is calculated. Federal income tax is calculated based on the W-4 you
fill out: https://www.irs.gov/pub/irs-pdf/fw4.pdf
What happens
if I think the federal tax amount should be different? The best source will be
your accountant. They know your tax situation best and guide you in filling out
your W-4. Another option is checking the IRS tax withholding calculator here: https://www.irs.gov/individuals/tax-withholding-estimator.