July 31 (Reuters) - Financial services and insurance

provider CBIZ ( CBZ ) said on Wednesday it would buy Marcum, one

of the biggest accounting services provider in the United

States, in a $2.3 billion deal.

Marcum, founded in 1951 and based in New York, provides tax,

attestation, accounting and advisory services.

Its attestation business - which reviews companies'

financial forecasts and other information - would be bought by

Mayer Hoffman McCann, a separate accounting firm.

The deal is expected to close in the fourth quarter of this

year, CBIZ ( CBZ ) said.