Look at the tables starting on page 46 to see what changing allowances will do ... first find your pay period for the single or married charts then look for your gross income for that pay period ...then look at the allowance columns
if I change my status on my w4 to married how will this affect my paycheck and w2 taxes. my wife is stay at home mother and does not have a job.
That link is a year old. If you change to Married they will take out less withholding. Which may be ok if you got a big refund last year. Your refund won’t be so big.
She probably was posting publication 15. There is withholding tables at the end
<a rel="nofollow" target="_blank" href="https://www.irs.gov/pub/irs-pdf/p15.pdf">https://www.irs.gov/pub/irs-pdf/p15.pdf</a>