Paragraph (p) of Subsection (1) of Section 4 of Chapter 32 of the General Laws is hereby amended by striking out the first sentence thereof and inserting in its place the following sentence: -

Any member of a contributory retirement system who is engaged in a teaching position and holds a certificate issued by the department of education or is exempted from the requirement of certification and who was previously engaged in teaching pupils in any non-public, private special educational school approved by the commonwealth, if the tuition of pupils taught was financed in part or in full by the commonwealth shall, before the date any retirement allowance becomes effective for him, establish such service as creditable service by depositing into the annuity savings fund of the system of which he is a member in one sum, or in installments, upon such terms and conditions as the board may prescribe, an amount equal to five per cent of the compensation received by him during such period of service plus regular interest to the date of such deposit for such previous period, or most recent portion thereof, as he may elect.