Proposed "women's rights" amendments to the Social Security Act could cent from $4.5 billion to $19.7 billion a year and force another upturn in Social Security taxes, according to a study by the Department of Health, Education and Welfare.

A task force appointed by Secretary Joseph A. Califano Jr. examined various methods of altering Social Security to answer complaints that some women are being cheated on benefits because no credits are given for time spent taking care of home and children.

The various plans studied would either give them "homemaker" credits or make their husbands split earnings records with them so they would have an independent right to Social Security benefits.

The study made no recommendation and didn't spell out the dollar costs of each proposal. But an appendix noted HEW computer estimates of the cost of each as a long-range actuarial percentage of payrolls throughout the nation subject to the Social Security payroll tax.

Based on the $1 trillion national taxable payroll expected in a year or so, the most expensive proposal, a version of the bill being sponsored by Reps. Don Fraser (D-Minn.) and Martha Keys (D-Kans.), would work out to 1.97 percent of payroll or $19.7 billion a year when fully phased in, some years in the future.

To finance this would require the employer and employee - in the case of a worker making $10,000 a year - who now pay $605 a year each in Social Security taxes to raise their contribution by about $98.50 each.

Fraser, in a statement, said he considered the HEW estimates too high, superficial and based on "erroneous assumptions" about how his plan would work.

he Fraser-Keys plan is designed for the period of life when a woman stays home and tkes care of house and children either full-time or part-time. It adds up the earnings of husband and wife ( even when the wife earns nothing) and then splits the earnings records in two as joint property, giving half to each. Alternatively, each could receive wage credits toward retirement equal to 75 percent of the rotal taxes earnings of the higher-paid of the two. Because of the way benefits are structed and eligibility is figured, this will result in higher total benefits than the current system.

The woman would have her own earnings record and entitlements to benefits even if she stayed home throughout her married life. She wouldn't have to depend on receiving a wife's benefits (equal to 50 percent of her husband's) after he retired. If they were divirced, she would get benefits on her own and they would be equal to his since each would have half the total earnings credit.

The plan is now being revised to cut its costs without losing the basic income-splitting principle.

Here are some other proposals studied and their costs:

Bella Abzug and Barbara Jordan plans give a woman "homemaker credits" for keeping house, just as of she had worked in a job with a cash income subject to the Social Security tax. Abzug bases the credits on the minumum wage, Jordan on median wage for women in paid jobs. Abzug plan cost 0.52 percent of payroll ($5.2 billion) a year, Jordan 0.62 percent ($6.2 billion).

Working spouse's benefit plan, designed by House Ways and Means Committee Republicans, aims to supplement the income of a working wife whose retirement benefits, based on her own earnings, are less than the 50 percent extra spouse's benefit she would receive when her husband retired even if she had never worked at all. She would be given the larger of either her own earned benefit or her spouse benefit, plus 25 percent of the smaller of the two. Cost: 0.83 percent of payroll or $8.3 billion a year.

Martha Griffiths plan is similar to Fraser-Keys but computes benefits less generously. Cost: 0.45 percent of payroll, or $4.6 billion.

Robert Ball plan, designed by former Socials Security Commissioner, woukld increase individual benefit to 112.5 percent of current maximum, but reduce wife's benefit based on husbands's earings record from 50 percent extra to 331/2 percent, Cpst: $15 billion.

Rita R. Campbell plan would wipe out all wife/husband and widow/widower benefitss based on spouse's earnings records and give wife up to three years of earnings credit for each of first two children. It assumes women will work full-time except for six-year child-care interval. This would actually reduce benefits for many wives and widows and save $12.1 billion a year - the only plan to make any savings.