Sometimes a budget is significant more for what it omits than what it includes.

That’s the case with the $34 billion spending blueprint approved Thursday by the Massachusetts Senate, which wisely chose to pass its budget without a proposal to allow the Department of Revenue to hire outside tax auditors and pay them a portion of what they recover.

The budget proposal also replaces two existing health care assessments with a new Employer Responsibility levy and does way with the Health Insurance Responsibility Disclosure (HIRD) form as Massachusetts prepares to replace its 2006 health care reform with the federal Affordable Care Act.

A conference committee will now hammer out differences between Senate and House versions of the budget for the Fiscal Year that begins July 1.

Senators adopted an amendment from Senator Michael Rodrigues, D-Westport, that struck the so-called “contingent contracts” provision that had been added to the budget in an outside section. Rodrigues noted on the Senate floor that the National Conference of State Legislators, the Securities and Exchange Commission and and the American Institute of Certified Public Accountants all reject the use of contingent contracts.

The AIM Taxation Committee had urged the Senate to reject the provision.

“The proposal was bad public policy,” said John Regan, Executive Vice President of Government Affairs at AIM.

“An auditor should have no financial stake in the outcome of an audit. The conflict of interest is readily apparent and should trouble policy makers concerned about tax fairness and Massachusetts reputation for its tax climate.”

The Senate budget represents a 4.2 percent spending increase over the current fiscal year. The document anticipates using between $500 million and $800 million in new taxes for transportation currently pending before a separate Beacon Hill conference Committee.

AIM has maintained throughout the debate that lawmakers should fund transportation improvements with transportation-specific sources of revenue rather than business taxes such as those proposed for computer software. The association nevertheless believes that the legislation passed by the House and Senate takes positive steps toward fixing the transportation system without crippling increases to the income tax or other broad-based levies.

The Senate budget includes a $50 per employee medical assistance assessment on employers that was filed by Governor Patrick and included in the House budget.  The new fee replaces the $67.20 Medical Security Trust Fund assessment.  The Senate did not support an AIM amendment to require legislative approval for any increases to the assessment and gives the authority to increase the fee up to 5 percent per year to a rate review board.

As part of the package for this new assessment, the Senate budget eliminates the fair-share contribution and the requirement that employee Health Insurance Responsibility Disclosure forms be collected and retained by employers.

Senators followed suit with the House in voting to postpone implementation of the so-called FAS 109 deduction instead of eliminating it as the administration proposed. FAS 109 is an accounting standard that requires that financial statements reflect the tax consequences of all book/tax differences. The deduction was adopted as part of the 2008 debate over adoption of combined tax reporting in Massachusetts.