Prior to his inauguration, Biden promised that his administration would record 100 million shots of COVID-19 vaccine within his first 100 days in office.
As the vaccination program progresses, the administration believes it will only get more hard to sustain the current pace of about 3 million shots per day.
The goal is being achieved more than a week before Biden hits his 100th day in office as his administration accelerates vaccination programs amid a surge of new infections.
It is not clear whether Mr Biden would consider sharing more AstraZeneca doses before the United States has enough vaccine.
The new tax credit is part of the government's quest to buttress efforts in the private sector aimed at encouraging vaccination, especially as supply of the shots catches up with demand and issues of access and hesitancy come to the fore.Large employers from American Airlines to Target have unveiled incentives for employees to get vaccinated, from an extra day off next year to free rides to vaccination sites.
Biden announced a tax credit for small businesses to provide paid leave for those getting vaccinated or potentially needing to take time off to recover from side effects.
The tax credit will apply to businesses with fewer than 500 employees.
Biden said, "No working American should lose a single dollar from their paycheck because they chose to fulfill their patriotic duty of getting vaccinated".
On Wednesday, he announced, "When tomorrow's vaccine - vaccination numbers come out, it will show that, today, we did it".
The White House is calling on larger employers, which have more resources, to provide the same benefits to their employees, and to institute vaccine education and encouragement campaigns so that their workers get shots.
"The progress we've made has been stunning", he said.
Biden said he talked with Canadian Prime Minister Justin Trudeau for about 30 minutes on Wednesday.
"We're looking at what is going to be done with some of the vaccines that we are not using", Mr Biden said.
He added. "We don't have enough to be confident to send it overseas now". A third of USA adults are fully vaccinated, as well as 26% of the population overall, it said.
By the time Biden was inaugurated on January 20, the US had already administered 20 million shots at a rate of about 1 million per day, bringing complaints at the time that Biden's goal was not ambitious enough. Still, it was generally seen within reach, if optimistic.