City Council Speaker Peter Vallone, who also is a Democratic candidate for mayor, next week will propose boosting tax rebates for co-op and condominium owners, The Post has learned.

Under Vallone’s four-year proposal, next year’s rebates would be increased by $167 for lower-valued units, and by $105 for higher-valued ones.

By 2005, they would average an additional $977 for lower-valued units and $515 for higher-valued ones.

This year, some 303,000 owners of co-ops and condos will receive an average abatement of $738 for lower-valued units and $278 for higher-valued ones.

Vallone and the council want to increase the abatement because co-op and condo owners still pay more in real-estate taxes than owners of equally valued homes.

The tax-abatement program costs the city $185 million. The price tag for Vallone’s proposal would be $222 million in 2002 and $257 million in 2005.

Martin Karp, chairman of the Action Committee for Reasonable Real Estate Taxes, a group composed of condo and co-op owners, said: “We endorse the Vallone program as it recognizes that the disparity in real-estate taxation still exists.”

The measure is expected to win easy council approval.