The photo depicts the two smiling at Apple's new headquarters in Cupertino, California, and comes just days after Cook's visit to Washington D.C.
"Glad to visit Apple HQ with Tim Cook. Thank you for your commitment to invest 350B in USA! #TaxCutsJobsAct," he wrote on the social media platform.
Apple in January made a series of pledges to invest in the U.S. economy, due in part to incentives reaped from the "Tax Cuts and Jobs Act." The company said it would open a new campus, create 20,000 jobs and repatriate most of its overseas cash, which comes to well over $250 billion. In total, Apple said its economic contributions over the next five years tally to about $350 billion.
The Treasury Department did not immediately return CNBC's requests for comment. Apple declined to comment.
Earlier this week, Cook made the rounds on Capitol Hill in Washington, D.C., as he does from time to time, but did not testify before any major committee. Apple didn't specify why the CEO visited on Tuesday, but NBC News did confirm he had a lunch meeting with Senator Mark Warner, a staunch advocate of privacy and cybersecurity.