Section 4. Every person regularly or habitually operating motor vehicles upon the highways of any other state or states and using therein fuel or special fuels purchased or acquired in this commonwealth may, within two years of the date when the fuel or special fuels were purchased or acquired, apply in writing to the commission, upon a form approved by it and containing or accompanied by such further information as it may require, for a credit or refund equal to the tax on said fuel or special fuels actually paid to the state or states in which it is used, not to exceed, however, the excise imposed by this commonwealth on the use of such fuel or special fuels. Such credit or refund may be allowed subject to subsequent verification and audit, provided, however, that the commission may require such applicant to file with it a bond, with a surety company authorized to transact business in the commonwealth as surety, in such amount as the commission may determine, to secure repayment to the commonwealth of any overpayment of such credit or refund, together with interest at the rate of eight per cent per annum from the date of such overpayment. No credit or refund shall be allowed under this section for taxes paid to any state which imposes a tax upon fuel or special fuels purchased or acquired in this commonwealth and used on the highways of such other state and which does not allow a similar credit or refund for the excise paid to this commonwealth on fuel or special fuels purchased or acquired in such other state and used on the highways of this commonwealth.