The revaluation will enable the city to impose separate tax rates on commercial and residential property. By state law, the city is forbidden to have multiple rate unless its property has been assessed at full value.

Before revaluation, the city generally valued commercial properties higher than residential properties. It was a loose city policy that businesses bear a heavier responsibility than residents for the city's expenses, officials explain.

In those years, the clubs were probably not considered commercial ventures and so their assessments would not have fudged upwards, says Peter Helwig, an official in Cambridge's assessor's office.

But under the new rate structure, state law will require that private clubs be considered commercial properties. The difference is significant: Helwig estimates that Cambridge's commercial tax rate for the year ending next July will be $31.77 per thousand dollars worth of property. The residential rate will only be $17 per thousand.

Already three Harvard final clubs have registered complaints about the new system, says an official involved with the revaluation. The official refuses to name the clubs or describe the results of their complaints.

The leap in property taxes on the University's chunk of the Fly Club garden may be one of the most dramatic in all of its enormous real estate portfolio, since it can claim exemptions on most of its land. It cannot on the Fly garden because that land is not used for educational purposes, Rosen says.

Last year's tax rate was $198 per thousand dollars, on the property's old, undervalued assessment of $26,000, for a total levy of $5158. With next year's estimated commercial rate of $31.77 per thousand and the new assessment of $660,400, the University's next tax bill on the land will be more than $20,000.

All the final clubs face similar hikes. Their old assessments ranged from $38,000 for the Owl Club to $112,000 for the Porcellian (which includes the space it leases to the J. August store). This resulted in taxes last year ranging from $7524 to $21,515.60.

The new assessments have resulted in values ranging from $403,000 for the Phoenix to $1,067,200 for the Fly. The new range of taxes will run from about $12,800 to about $33,600.

The clubs have essentially one place to run for new infusions of income to offset their new tax burden the pockets of their alumni. Their task as fundraisers is hampered by the fact that since they are not public charities, they can not offer tax deductions for contributions.

At the Spee, for instance, most alumni donations come in the form of $40 to $50 additions to the kitty, with larger amounts coming in only occasionally, according to one alumnus.

Some clubs, like the Spee, have toyed with the idea of allowing women to join in order to increase the pool of dues-payers, and eventually alumni. The Spee has also come up with another strategy for finding new income: it recently agreed to lease some of its first-floor space to Schoenhof's bookstore, which is about to be evicted from its current Mass. Ave. site.

Adam S. Cohen helped prepare this report.

Tomorrow: The Harvard administration's links to the final clubs.

Since 1956 Harvard has paid more than $85,000 in taxes on the Fly Club's garden--most recently a $5148 levy for the 1982-83 fiscal year. According to the city's most recent property assessment, the land's current value is $660,400.