The state’s business tax, also called the margin tax, is yielding 10 percent less revenue this year than last, Comptroller Susan Combs’ office said Wednesday. The tax has brought in $3.6 billion this year, down from $4 billion at the same point last year, said Combs spokesman R.J. DeSilva. Last year, 93 percent of the money came in by May, DeSilva said. Original estimates were that the tax this year would produce the same amount as last year – $4.3 billion.