The Social Security tax increase the House approved on Thursday would, if enacted, be one of the largest peacetime tax increases in U.S. history, rivaled in recent years only by the levies during the Korean and Vietnamese wars.

The House bill would add an estimated $208 billion to the taxes of workers and employers combined over the next 10 years, and more thereafter. That is in addition to sizeable tax increases already scheduled under present law. It works out to an average of $10 billion a year in extra taxes on both employers and employees.

Most of this money would flow between generations, from younger workers to older retirees. In that sense the bill is a first installment on the painful inter-generational politics the United States has been warned to expect in coming years as the population ages and the number of retirees rises in relation to the number of workers on whose wagers these retirees depend.

The emphasis Thursday was on the effect the bill would have on higher-income workers; those at the highest income levels would have their Social Security taxes tripled in the next 10 years.

It went almost unnoticed that Social Security taxes will also go up 21 per cent fro the average and poorest American workers.

The rates they pay - most of them on all their earnings - would rise under the bill from this year's 5.58 per cent to 7.1 per cent by 1986, and go still higher later. For many Americans, Social Security taxes have already passed the federal income tax as the largest they must pay; the bill would accelerate this.

Yet while House members found it politically painful to vote such taxes, they plainly also found it painful to contemplate the aternative - a drying up of the SOcial Security trust funds, and an eventual reduction in the beneftis that now go out under this giant system to 33 million Americans - one in every seven.

"We can't let the old people down," intoned House Social Security Subcommittee Chairman James A. Burke (D-Mass.) repeatedly when Reps. Barber B. Conable Jr. (R.Y.), William A. Steiger (R-Wis.) and others warned that the tax increases would be a "staggering load" for businesses and employees.

The House further eased the pain by deferring most of the contemplated tax increases until after the next election, and, it is hoped, also after the economy recovers more completely from its reverses of recent years.

Still, there was a sense that the Social Security tax may be reaching its outer limits. Rep. Ricbard A. Gephardt (D-Mo.), one of the sponsors of the bill, virtually conceded as much when he told the House, "We've raised the taxes to the breaking point."

The debate on the bill and statistics on general taxes paid by the American worker underscore two facts about Social Security: the heavy load it lays on the working person - even the low-income working person - and the huge role that Social Security now plays in the economy.

A dozen years ago the maximum amount of wages subject to the payroll tax was $4,800 and the tax rate was 3.625 per cent each on employers and employees - a top tax of $174 each. Today teh maximum tax is $965. Existing law would drive those figures up, but the new taxes voted by the House raise the maximum taxable wage still further to $42,600 by 1987 with the rate of 7.10 per cent - for a maximum tax of $3.025 for the high-income worker.

This means very heavy new taxes on high-income workers. But the lower-income worker will also suffer. A married taxpayer with spouse and two children, making $10,000 a year (about the average nonfarm wage in private employment today) pays $585 in Social Security taxes. His Social Security tax will go up to $710 by 1987.

Such a worker today is probably paying only $446 in federal income tax, so his Social Security tax is higher than his income tax. A married axpayer with spouse and two children doesn't pay any federal income tax at all on the first $7,200 of earnings. But such a worker would be paying $421 Social Security tax.

These figures reflect in miniature the larger story of Social Security's tremendous role in the economy. Benefits for many people are the chief source of income. Over 100 million workers are subject to the Social Security tax.

Benefits paid out in 1977 will be about $87 billion in cash payments for support of old-age and disability pensioners, plus over $22 billion for Medicare - and a few billion short of that will be taken out of the economy thru the payroll tax to finance the benefits.

Why are costs outrunning tax income? Partly, because benefits have grown substantially over the years, although they still aren't princely.

The average man and wife on Social Security today get a combined benefit of $400 a month; the maximum for a husband and wife retiring now is about $690.

Benefits now are relatively larger for lower-paid workers than for those at higher levels. An average worker's first benefit check on retirement is about 45 per cent of his last pay check. For a worker at the minimum wage this "replacement ratio" is about 60 per cent, for a worker at the tax cutoff about 30 per cent.

The House voted to scale down benefits faintly in the future, so the replacement ratio for the average worker would gradually fall to, and then remain at, about 43 per cent.