The Internal Revenue Service yesterday told 19,000 of its 86,000 employes that they will be furloughed involuntarily Wednesday until further notice because there is no money to pay their salaries.

Unless the congressional Appropriations Committee chairmen approve a transfer of funds over the long Labor Day weekend, the tax collectors will be the first federal employes to take unscheduled, unpaid vacations because President Reagan vetoed the $14.1 billion supplemental appropriations bill last Saturday.

Furloughs will be a reality for thousands of employes in other government departments and agencies by the middle of the month if Congress does not override the veto or pass a new supplemental appropriations bill acceptable to the president, federal officials said yesterday.

Budget officers in several departments contacted said they were checking their balance sheets to see how many days they have left.

The vetoed appropriations bill included $260.4 million for IRS salaries. About three-fourths of the employes scheduled to be furloughed collect delinquent taxes, IRS officials said. That particular office produced $7.7 billion in revenue for the federal government last year.

The other IRS employes to be furloughed investigate criminal tax cases and check the tax status of employe benefit plans and nonprofit organizations.

Money in other IRS accounts could be shuffled to pay salaries, but this requires written permission from the chairmen of the House and Senate Appropriations committees, and they have been out of town along with the rest of Congress.

Reprogramming authority could be granted over the weekend or on Tuesday, thereby eliminating the furlough threat.

A Treasury Department source said that Rep. Jamie L. Whitten (D-Miss.), chairman of the House Appropriations Committee, and Sen. Mark O. Hatfield (R-Ore.), chairman of the Senate Appropriations Committee, were asked Aug. 27 to grant reprogramming authority, "but we have not heard back."

That was the day the White House let it be known that Reagan would veto the bill. A congressional source said, "You know, this is not the kind of thing they're going to solve over the telephone. They're going to have to sit down and look us in the eye, and Congress is going to have to be back in town for that to happen."

Many members of Congress were outraged by the Reagan veto, and instantaneous cooperation between the White House and Capitol Hill is not expected when Congress reconvenes Wednesday.

The IRS employes to be furloughed are supposed to spend Tuesday closing their offices.

"It's not anticipated that the orderly shutdown of services will take more than eight hours," an IRS spokesman said.

The employes to be furloughed first learned of it yesterday.

"We've been hoping for some way to resolve the problem short of doing this," said Treasury spokesman Marlin Fitzwater, "but it just hasn't worked out. We haven't been able to come up with enough money. This is a fairly serious move, and not one that we wanted to announce until we were sure we had to take it."

The big trouble day for the rest of the government is Sept. 15, when the Department of Defense next has to meet a payroll. The military services are, for the most part, considered essential and thus not subject to furlough.

The problem for all departments and agencies, from Defense to the Smithsonian, is that Congress passed a federal pay raise last Oct. 1 but did not provide all the money needed to cover it until the supplemental appropriations bill was passed.

Thus, with the 1982 fiscal year coming to an end Sept. 30, agencies have been running out of money because they have paid salaries at the higher rate.

A special accounting device was approved so the Pentagon could meet its Aug. 31 payroll if Reagan vetoed the supplemental appropriations bill. Another tactic was devised to keep the tiny Federal Labor Relations Authority afloat after it appeared its employes would have to go out this week.

According to a scorecard being kept by the Office of Personnel Management, the lack of supplemental money could bring furloughs across the government.

The biggest problem outside the Defense Department's 2 million employes would be 100,000 employes of the Health and Human Services Department, who would be furloughed Sept. 16.

The Education Department would have 4,300 employes furloughed Sept. 14, the Labor Department 6,000 employes on Sept. 27, and NASA 20,000 employes sometime late this month.

"Everybody is trying to find money to move into payroll accounts," said Pat Korten, a spokesman for the Office of Personnel Management. "So those furlough dates could slip later into the month."