The compensation of the experts, clerks, and other employees of the county boards of revision shall be paid monthly upon the certificate of the county auditor or board. The contingent expenses of the auditor and board, including postage and express charges, their actual and necessary traveling expenses, and those of their deputies, experts, clerks, or employees on official business outside of the county, when required by orders issued by the department of taxation, shall be allowed and paid as are other claims against the county. The compensation and expenses may be paid from the real estate assessment fund pursuant to section 325.31 of the Revised Code.