How can the President stop a tax law?

He can do so (just as almost ALL previous Presidents have done) by Executive Order....

(And Congress can overturn such orders if they can muster a 2/3rds majority vote)

He allowed them another year to file all the PAPERWORK and he waived the $2000 fines of the ACTUAL corporations affected (see below). It was something that administration officials and the small % of corporations effected had been working to avoid. You ***** about the those fines/taxes/whatever .. saying those company's will have to pay too much for insurance and employees will suffer .. well that didn't happen and now your'e complaining about it?

This ONLY effects Corporations with more than 50 employees and because most were already in compliance we're talking about only 4% of THOSE corporations.

You might want to find some REAL information before you ask a question like this .. you won't look so ignorant.

The President has nothing to do with implementing the tax penalty. He and the Dept of Health & Human Services which is the federal agency in charge of the insurance plan will delay the implementing that provision of Obamacare until 2015. The IRS will impose the tax penalty in 2015 instead of 2014.

He can only sign or veto bills that pass his desk.