What's new in the bookstores to help you figure your taxes

Writing tax books must be a good way to earn income and owe more taxes. These volumes continue to multiply. This year's crop includes the perennials, such as Sylvia Porter's 1984 Income Tax Book (a publicity blurb says 265,000 copies have been printed), and H & R Block's ''bestseller'' 1984 Income Tax Workbook. There are also newcomers.

One is aimed at the nation's majority: women. It's titled, Taxable You: Every Woman's Guide to Taxes, by Mary L. Sprouse. This Penguin book (priced at a tax deductible $8.95) assures its readers that taxes are easy. ''Learning the basics of tax law is like learning to swim,'' writes this former Internal Revenue Service auditor. ''Once you get your feet wet and realize drowning requires active cooperation, you're on your way to a decent dog paddle. . . . Taxes are a lot less frightening than riptides and the bends.''

She adds: ''Taxes, like accounting, war, and football, have traditionally been men's games.'' But, she argues, the woman of the 1980s enjoys increased economic independence and responsibility and can use the tax laws ''to avoid costly financial mistakes, and to reap the maximum tax benefits from your particular lifestyle and marital status.''

Ms. Sprouse admits that the tax law is neutral as to sex. But men and women traditionally play different roles with certain tax consequences. So, she says, women have specialized tax needs and this book emphasizes those aspects of the tax law that are more likely to be relevant, such as those touching on widowhood , divorce, alimony, child support, child care, and so on.

The author tries to write with a light touch, sometimes becoming too cute. The book is not a tax manual, though it does run through the preparation of form 1040A, a short tax form. Published as a large paperback, it contains no tax forms.

Another publication aimed at a special audience is Fear of Filing: A beginner's guide to tax preparation and record keeping for artists, performers, writers and freelance professionals, 1984 edition, by Volunteer Lawyers for the Arts, edited by Theodore W. Striggles and Barbara Sieck Taylor (Dodd Mead, New York, $12.95). It attempts to be funny, not too successfully. For instance, the introduction concludes: ''Do not attempt to assimilate Fear of Filing after meals or while other pleasurable activity is available. When ingested in quantity, the subject matter has been proven harmful to unborn creative ideas. Taken in moderate doses without enthusiasm, however, it appears to be of some therapeutic use in helping to provide an understanding of the business world and relative control over hysterical tax attacks.''

Other tax manuals are better overall, but this one concentrates on aspects of tax law most relevant to its specialized audience, such as royalties, awards, out-of-town travel and local transportation, professional fees, and so forth. It discusses in detail the differentiation made by the IRS between a ''business'' and a ''hobby.''

The tax forms, both blank and filled in with an example, that are published in the book are, unfortunately, for 1982.

Among the perennials, both Sylvia Porter and H & R Block's manuals note tax changes of interest in 1983 returns. Probably most cheering, personal income tax rates are down about 9 percent across the board from rates for 1982. Also the so-called marriage penalty - under which a married couple could end up having to pay more in taxes than would be due if they were not married and had filed single returns - was reduced once more. For 1983, some 10 percent of the lower-earning spouse's earned income, up to $3,000, can be deducted from taxable income.

Further, those using the zero-bracket amount (standard deduction) and not itemizing deductions can deduct 25 percent of their charitable contributions up to $100. And the optional standard mileage rate deduction for the first 15,000 miles of business travel has been raised from 20 cents a mile to 20.5 cents.

Less happily, taxpayers will not be able to deduct as much of their unreimbursed 1983 medical or other such expenses. They can't deduct up to $150 of medical-insurance premiums, which was allowed in their 1982 return. Moreover, the portion of 1983 medical expenses that is not deductible has been increased from the 3 percent of adjusted gross income in 1982 to 5 percent in 1983.

Casualty-loss deductions are also trimmed. Each casualty must still be reduced by the same $100 as in 1982, but further reduced by 10 percent of your adjusted gross income to arrive at the amount that is deductible as a casualty loss.

In other words, Congress has succeeded in eliminating deductions for all but major medical expenses or casualty losses.

There are other changes involving office-at-home deductions, tougher penalties for substantial understatements of income and late filing, and so on.

Sylvia Porter's book claims to be the only one including 1983 tax forms. That's not the case. H & R Block's workbook also has the forms. The Block publication, expanded this year, is somewhat more comprehensive than the Porter book. It also costs $5.95, $1 more than the Porter manual. Both are clearly written.

Recognizing a good business, H & R Block has two new tax publications: The Complete Personal Tax Record Book ($5.95) and The Complete Book of Income Tax Deductions (also $5.95). The first provides a simple record-keeping system, organized to follow the tax forms. The second lists hundreds of deductions, giving examples and advice based on recent Tax Court and IRS rulings.

The latter book does not match, at least in number of deductions listed, a perennial publication, Take It Off, by Robert S. Holzman (Harper & Row). The Holzman book claims to list 2,782 deductions, up 509 from the year before. It also costs more - $8.95 paper, $17.95 cloth - and will take more time to run through than the Block book.

There's another less-comprehensive list of tax-saving techniques: Perfectly Legal: 350 Foolproof Methods for Paying Less Taxes, by Barry R. Steiner and David W. Kennedy (John Wiley & Sons, $7.95). At the end of the book, the authors have printed selected pages from the Audit Technique Handbook for Internal Revenue Agents, presumably to help taxpayers survive audits with less financial damage.

The older basic manuals have been joined by another this year: Miller's Personal Income Tax Guide, by Martin A. Miller, L. Harold Levinson, and Laura P. Stephenson (Harcourt Brace Jovanovich). It is more expensive ($7.95) and bigger (388 pages). It boasts of an ''exclusive Walkthru Method that explains every single line'' of form 1040, which could be helpful for the tax novice. The back of the book includes some blank pages for notes and computations. But there are no blank tax forms to use if yours failed to arrive or an IRS office is not convenient.