For most people income taxes are a once-a-year headache.Yet, for hundreds of thousands of others taxes are a year-round concern. They are the lawyers, accountants, lobbyists, policy planners, analysts, teachers, writers, publishers and preparers for whom tax-related issues constitute a primary livelihood.

It is virtually impossible to calculate the size and scope of the tax industry. The Bureau of the Census has no "tax" bracket under occupations. Few companies segregate their revenues according to subject. Americans spent some $287.5 billion paying their taxes last year; how many more billions did they spend promoting, publishing and preparing them?

The nation's capital is not only the home of the Congress which makes the tax laws and the Internal Revenue Service which carries them out, it is the mecca of tax lobbyists. The 1980 guide of Washington representatives lists 39 organizations with offices here that are eager to testify on tax issues -- and that is obviously only the tip of the iceberg. Last summer Joseph Whitebread Jr. and Thomas F. Field published a Compendium of Organizations Seeking to Influence Tax Policy. It studied the major groups and sampled some of the minor ones.

Whitebread and Field, writing in Tax Notes, divided the influencers into four categories: business-oriented, academically oriented research, "balance-the-budget" groups and all others. They concluded that the business and balanced budget conservatives outspent the liberal and labor groups by $7.5 million to $300,000. Corporations and individuals are the major source of support; only a handful of foundations make major grants. Here is a sampling:

National Tax Limitation Committee, founded in 1975, has a budget of $3 million, and primarily grass roots support. It recently succeeded in getting a constitutional amendment introduced to limit the growth of the budget to the growth of the gross national product.

Tax Executives Institute, which says it does not lobby, has a staff of nine and a budget of $500,000. Its membership is corporate tax managers. In addition to its scholarly publications, it runs a tax school and conducts conferences.

Tax Foundation Inc., which says it does not lobby, was founded in 1937, has 29 employes and a budget of $1.2 million, supported by big business. Its staff, comprised mainly of economists, analyzes tax policy, such as the effect of taxation on research and development. It publishes Monthly Tax Features and Tax Review.

Taxation with Representation Fund, established in 1970, has a staff of 30 composed mainly of lawyers and a budget of $750,000. Liberally oriented, it claims to represent the ordinary taxpayer. Its immediate goal is to prevent the Reagan administration's proposal from being loaded down with breaks for special interest groups. It publishes Tax Notes magazine.

National Taxpayers Union was founded in 1969 and has 22 employes and a budget of $1.8 million from conservative grass roots support. Its primary concern is passage of a constitutional amendment requiring a balanced budget. It publishes a monthly newsletter, Dollars and Sense.

Tax Reform Research Group was founded in the 1970s by Ralph Nader. Now part of Congress Watch, it has a staff of five and a buget of $100,000. Its concern is reduction of taxes for low- and moderate-income persons.

National Tax Equality Association, founded in 1943, has a budget of $250,000 and is supported by small businesses. It aims to eliminate tax advantages for agribusiness, and rural electric and telephone cooperatives.

National Council for a World Peace Tax Fund has a staff of three and a budget of $30,000, supported by religious and pacifist groups. Its objective is to provide a legal alternative for conscientious objectors who do not wish their taxes to go for military activities.

Thomas Jefferson Equal Tax Society, founded in 1974, claims support from 10,000 middle-class citizens and self-employed business people. It refuses to reveal its budget because it does not recognize the IRS and the right of the federal government to collect income taxes.

Unlike the tax lobbies, the tax publishers are primarily located in other parts of the country. The biggest is Commerce Clearing House in Chicago, which had revenues of $151 million last year. About a third of that came from tax-related publications. Its publications of business and tax law are aimed at professionals. It employs 60 people in Washington.

Prentice Hall, a New Jersey book publisher, had revenues of $350 million last year. A spokesman said the business and professional books section, which includes tax materials, did $120 million in sales in 1979, but he had no more recent breakdown. It has a staff of 16 here.

Research Institute of America, located in New York, has a dozen or more tax publications, of which Research Institute Recommendations is the largest. Written in lay language for business executives, it has a circulation of 150,000. The institute, which has three people working on taxes here, refused to reveal any financial information.

The Bureau of National Affairs (BNA) is a private publishing corporation located in Washington. Its tax-related revenues last year amounted to about $15 million. It employs about 1,000 people. BNA publishes Daily Tax Report and Daily Report for Executives, which also contains tax news. The former reports legislation, court decisions, and IRS regulations for tax professionals; the later, which costs about $3,000 a year, is aimed at top executives in corporations, trade associations and law firms.

Tax Management Inc. is a BNA subsidiary. It publishes 300 portfolios or tax treatises in four different groups: income taxes, estate and gift taxes, foreign income taxes and compensating planning, as well as other journals. It has 25,000 subscribers.

Asked how many tax books, newsletters, journals and other publications there are, Tax Management's editor, Benjamin Fassberg sighed, "There must be a hundred and one of them that come across my desk." Among those produced in Washington is the Kiplinger Tax Letter. Founded in 1925 and costing $42 a year, it has 90,000 subscribers, double the number it had a year ago. Its primary focus is the small businessperson, but much of the material, written in lay language, is devoted to personal taxes and investments.

Then there is Tax Exempt News, published by Capitol Publications. Its audience is nonprofit organizations. Its 1,000 subscribers pay $87 a year. And last, but not least, is the federal government itself. The Government Printing Office sold $1.3 million worth of IRS publications in 1980. A subscription to the Weekly Internal Revenue Bulletin, for example, costs $55.

As one publisher put it, the more the government tries to simplify taxes, the more we have to write about.And speak about.

Daily Tax Report's editor Ben Tyree estimates there is at least one major tax conference a day somewhere in the country. Typical is one the accounting firm of Arthur Young will hold in May for accountants. The three-day symposium costs $325 per head. Add travel and living expenses and the tax instruction industry becomes big business indeed.

The same growth that lobbies, publications and seminars have experienced in the past decade has been repeated at the academic level. George Washington University had two tax courses 10 years ago; today there are four graduate courses and two undergraduate courses. Instead of 40 students, there are 150. A typical course of three credit hours costs $125 per hour. Georgetown University's Business School, which now has one graduate and two undergraduate courses in tax, is seriously considering adding a tax major as part of its MSA degree in the fall of 1982. Associate Dean William G. Droms said the school has been approached by major accounting firms wanting to donate a tax library.