You mean your W2 not W4.
You have not filed yet for 2018? You will have to buy the desktop program or get forms from the IRS.
If you think your employer made a mistake then take it up with your employer.
You are probably comparing the wrong numbers. If you had a transportation benefit or you had tax deferred money taken out for a 401k or health benefit for example that number will be different then the amount on your last paystub.
Disclaimer: Not a tax professional. Information gathered from internet links. Anything dated in June 2019 was posted in prior years and is before the 2019 limits and changes.
