The answer is for a few reasons:

• Lenders did you make sure your in the same line of work
• lenders need to make sure you’re doing the same type of occupation
• lenders need to make sure you have a history of employment with that particular employer

Paystub’s are only part of the full financial picture, a lender needs to show to a mortgage loan underwriter in helping you buy a home. In other words, the Paystubs only represent the history of the last 30 days as well as the current year-to-date income. They don’t show the income that you made in the prior year and is your occupation is such where there is gaps in employment or if for example you only work 10 months out of the year, the Paystubs don’t show the full picture. Beyond that the and mortgage investors in the secondary mortgage market, Fannie Mae and Freddie Mac required W-2’s to show an ability to repay the loan. Its is a good thing the lender asks for a W-2 because they’re making sure that you can actually afford a house payment you’re setting yourself up to be obligated for.