Section 5.05 - Experience Rating(1) Benefits for partial unemployment shall be charged in the same manner as for benefits in total unemployment, except that no charge shall remain against the account of any subsidiary employer who timely protests and who shows to the satisfaction of the Commissioner that it has continued to employ a claimant during the weeks of his claim to the same extent that it had previously employed him. In the event that the subsidiary employer is liable for payments in lieu of contributions, then the principal employer will be charged to the extent possible as provided in M.G.L. c. 151A, § 14(d)(3) prior to any later charges to the account of the subsidiary employer.(2) Charges made to employer accounts as a result of benefit payments made on claims with effective dates after December 31, 1951, which payments are later discovered to have been illegally made, may be removed from the account of the employer who was charged for the specific weeks so paid; except that, if such employer has received a notice of claim filed and his failure to have returned such notice contributed directly or indirectly to the allowance of the illegal payments, the charges shall nevertheless stand on the account of such employer; provided further, that no adjustment of a charge made in error shall be made unless request for adjustment is made within the time specified in M.G.L. c. 151A, § 71(1).(3) In relation to an employer's account as of a computation date: (a) If an employer has no taxable wages but has a balance, such employer's reserve percentage shall be deemed to be zero positive if the account balance is positive; or, zero negative if the account balance is negative.(b) If an employer has a zero account balance, such employer's reserve percentage shall be deemed to be zero positive.(4) With respect to any claim filed, if any base period employer shall show to the satisfaction of the Commissioner that the worker became separated from his last employment with such employer solely for the purpose of accepting work with another employing unit by which he had been hired, charges with respect to benefits paid to such a worker shall not be chargeable to such employer's account but shall be charged to the solvency account.(5) Extended benefits paid to an individual under M.G.L. c. 151A, § 30A shall be charged in accordance with the provisions of M.G.L. c. 151A, § 14(d)(3) to the accounts of the employers who reported base period wages which were used to establish such benefits. The Commissioner shall compute such charges by dividing the wages paid the individual by the employer in the base period by the total wages paid the individual by all employers in the base period. Such charges shall be made to the accounts of the most recent and next most recent employers in the inverse chronological order of the base period employment of the individual, provided, that whenever it is found that such individual was in employment with two or more employers in any quarter of the base period and the order of such employment cannot be readily determined, the Commissioner shall prescribe the manner in which such charges will be made.