More than 140,000 firms have applied for help to pay their wage bill through the government's job retention scheme, which went live on Monday.
The programme funds 80% of workers' wages, up to £2,500 a month, if they are put on leave.
Speaking at the Downing Street press briefing, Chancellor Rishi Sunak said the money would help pay the wages of more than a million people.
But many more than that are expected to be "furloughed" due to the lockdown.
The Treasury said the system can process up to 450,000 applications an hour. Employers should receive the money within six working days of making an application, it said.
The chancellor said the scheme would help people who could have lost their jobs if they had not been furloughed.
Employers had made 67,000 job claims within half an hour of the system going live at 08:00, HMRC chief executive Jim Harra told the BBC's Today programme.
Mr Harra said: "The big payroll date this month is on the 30th, so employers can claim anytime today, tomorrow or on Wednesday, and there's time to get that money into their account for the 30th of April."
Mike Cherry, the national chairman for the Federation of Small Businesses said the system had "held up" under the weight of applications, adding that employers had generally found it straightforward to submit the information required.
"Of course this is only day one," he said. "The real mark of success for this scheme will be money in employer back accounts by the end of the month."