The city six years old property revaluation will be completed before the May mailing deadline for the next tax bills officials told the Cambridge City Council at a public hearing last night.

After failing to win approval from the state Department of Revenue for estimated figures prepared last fall, city assessors have worked with a special consultant called in by the state to correct the assessment Project Director Peter Helwig said the new figures will be sent to revenue officials by December 22.

The revaluation which officials have estimated will cost Cambridge $700.000 by the time the projects is completed, will allow the city to tax commercial, industrial the residential property at 100 percent of its value. The current tax rate is based on assessment of less than full value.

Helwig said that although Cambridge will be able to tax property assessed at full value the city's tax levy--the total amount it can raise in tax revenues--has been substantially reduced by Proposition 2.

When questioned by the eight councilors. Helwig refused to estimate the image of residential property taxes may increase or decrease.

"You could probably find isolated examples that would blow your mind," Helwig explained.

In the hearing, Councilor Thomas W. Danchy expressed concern that the revaluation would equalize the current differences between taxes on residential and commercial property. Business and industrial properties now bear a disproportionate amount of Cambridge's tax burden.

But Helwig said a classification system would allow the city to continue to pass along a larger share of the taxes to commercial plots. He added that state statutes allow Cambridge to tax business at 150 percent of their assessed value and drop residential taxes as low as 65 percent.

If the revenue department approves the corrected figures city assessors will notify property owners of an estimate of their new tax, hold hearings in March to consider complaints, and present the final assessment to the council in early April Helwig said.

He added that the approval may be delayed because the revenue department is currently understaffed and seeking additional funds from the state legislature to hire more staff.