The Bluebirds will make their Barclays Premier League bow at West Ham on Saturday, 51 years after their last top-flight outing.
Malaysian businessman Tan vowed to back his manager in the transfer window after the club secured promotion back in April, and he has been true to his word.
The acquisitions of Danish striker Andreas Cornelius, Tottenham defender Steven Caulker and Sevilla midfielder Gary Medel have each raised Cardiff's record outlay, while John Brayford and Simon Moore have been brought in from Derby and Brentford respectively.
Tan has made it clear he expects to see a return on his investment, with Mackay still looking to make further additions to his squad.
But the Scot is comfortable with the pressures that go with his level of expenditure.
"He (Tan) has expected results from last summer," he said.
"When I was offered the job, it was a three-year plan. His task for me was to be promoted last summer. That's expectation, that's pressure, so I have had that. Football managers are under pressure every week."
He added: "I've broken the transfer record three times, but it's where we are as a club.
"It's not about looking back, it's about making sure we keep striving to push forward.
Source: PA
Source: PA