A key author of the new tax law said Thursday that he won’t judge its success just by the bonuses and raises that individual companies have been publicizing in recent weeks.

Such announcements are encouraging in the short term, said Texas Republican Rep. Kevin Brady, and, with improved business confidence, a sign that the tax cuts are working.

But in the long run, Brady said, he will gauge the law’s success by whether it encourages companies to bring back jobs, operations and headquarters from overseas, and whether it increases business investment.

“This tax reform is designed to leapfrog us, America, into the lead internationally,” said Brady, who is the chairman of the Ways and Means Committee that wrote the bill in the House. Brady also was chairman of the House-Senate conference committee that produced the final version of the bill.

In recent days, Republicans have claimed success for the law as companies have announced bonuses for employees and new investments, such as Apple’s announcement that it expected to hire 20,000 people and invest $350 billion partly because of the tax cuts.

“Tax reform is working, and it’s helping to improve people’s lives, which is exactly why we did it,” House Speaker Paul Ryan said Thursday.

Tax Foundation expert John Buhl, however, cautioned that it is not possible to draw conclusions about the law’s impact from announcements of one-time bonuses, or even short-term economic data such as jobs reports.

“We might not really know the full impact of the bill for several years,” Buhl said, noting that there is no easy way to distinguish the incoming economic data from what would have happened if the tax law hadn’t been enacted. The Tax Foundation, a nonprofit, generally favors lower tax rates and a broader tax base — meaning one with fewer deductions, credits, and loopholes.

It's certain that Republicans and Democrats will argue for years about how the tax overhaul affects jobs, wages, and the budget, as they did following the Bush tax cuts.

Buhl agreed with Brady, however, that the data on capital investment will be key in judging the law’s success.