(a) General rule. A day of service in the maritime industry which must, as a minimum, be counted for the purposes of determining a year of service, a year of participation for benefit accrual, a break in service and an employment commencement date (or reemployment commencement date) under sections 202, 203 and 204 of the Act and sections 410 and 411 of the Code by a plan that credits service by days of service rather than hours of service (as prescribed in § 2530.200b-2, or under equivalencies permitted under § 2530.200b-3) or elapsed time (as permitted under § 2530.200b-9), is a day of service as defined in paragraphs (a)(1), (2) and (3) of this section.

1. (1) A day of service is each day for which an employee is paid or entitled to payment for the performance of duties for the employer during the applicable computation period.

2. (2) A day of service is each day for which an employee is paid, or entitled to payment, by the employer on account of a period of time during which no duties are performed (irrespective of whether the employment relationship has terminated) due to vacation, holiday, illness, incapacity (including disability), layoff, jury duty, military duty or leave of absence. Notwithstanding the preceding sentence:

   1. (i) No more than 63 days of service are required to be credited under this paragraph (a)(2) to an employee on account of any single continuous period during which the employee performs no duties (whether or not such period occurs in a single computation period);
   2. (ii) A day for which an employee is directly or indirectly paid, or entitled to payment, on account of a period during which no duties are performed is not required to be credited to the employee if such payment is made or due under a plan maintained solely for the purpose of complying with applicable workmen's compensation (including maintenance and care), or unemployment compensation or disability insurance laws; and

   3. (iii) Days of service are not required to be credited for a payment which solely reimburses an employee for medical or medically related expenses incurred by the employee.

      For purposes of this paragraph (a)(2), a payment shall be deemed to be made by or due from an employer regardless of whether such payment is made by or due from the employer directly, or indirectly through, among others, a trust, fund, or insurer, to which the employer contributes or pays premiums, and regardless of whether contributions made or due to the trust, fund, insurer or other entity are for the benefit of particular employees or are made on behalf of a group of employees in the aggregate.

3. (3) A day of service is each day for which back pay, irrespective of mitigation of damages, has been either awarded or agreed to by the employer. Days of service shall not be credited both under paragraph (a)(1) or paragraph (a)(2), as the case may be, and under this subparagraph. Thus, for example, an employee who receives a back pay award following a determination that he or she was paid at an unlawful rate for days of service previously credited will not be entitled to additional credit for the same days of service. Crediting of days of service for back pay awarded or agreed to with respect to periods described in paragraph (a)(2) shall be subject to the limitations set forth in that paragraph. For example, no more than 63 days of service are required to be credited for payments of back pay, to the extent that such back pay is agreed to or awarded for a period of time during which an employee did not or would not have performed duties.

(b) Special rule for determining days of service for reasons other than the performance of duties. In the case of a payment which is made or due on account of a period during which an employee performs no duties, and which results in the crediting of days of service under paragraph (a)(3) of this section, or, in the case of an award or agreement for back pay, to the extent that such award or agreement is made with respect to a period described in paragraph (a)(2) of this section, the number of days of service to be credited shall be determined as follows:

1. (1) Payments calculated on the basis of units of time. In the case of a payment made or due which is calculated on the basis of units of time, such as days, weeks or months, the number of days of service to be credited shall be the number of regularly scheduled working days included in the units of time on the basis of which the payment is calculated. For purposes of the preceding sentence, in the case of an employee without a regular work schedule, a plan may provide for the calculation of the number of days of service to be credited on the basis of a 5-day workweek, or may provide for such calculation on any reasonable basis which reflects the average days worked by the employee, or by other employees in the same job classification, over a representative period of time, provided that the basis so used is consistently applied with respect to all employees within the same job classifications, reasonably defined.
2. (2) Payments not calculated on the basis of units of time. Except as provided in paragraph (b)(3) of this section, in the case of a payment made or due, which is not calculated on the basis of units of time, the number of days of service to be credited shall be equal to the amount of the payment divided by the employee's most recent daily rate of compensation before the period during which no duties are performed.
3. (3) Rule against double credit. Notwithstanding paragraphs (b)(1) and (2) of this section, an employee is not required to be credited on account of a period during which no duties are performed with a number of days of service which is greater than the number of days regularly scheduled for the performance of duties during such period. For purposes of the preceding sentence, in the case of an employee without a regular work schedule, a plan may provide for the calculation of the number of days of service to be credited to the employee for a period during which no duties are performed on the basis of a 5-day workweek, or may provide for such calculation on any reasonable basis which reflects the average hours worked by the employee, or by other employees in the same job classification, over a representative period of time, provided that the basis so used is consistently applied with respect to all employees in the same job classifications, reasonably defined.

(c) Crediting of days of service to computation periods.

1. (1) Except as provided in paragraph (c)(4) of this section, days of service described in paragraph (a)(1) of this section shall be credited to the computation period in which the duties are performed.

2. (2) Except as provided in paragraph (c)(4) of this section, days of service described in paragraph (a)(2) of this section shall be credited as follows:

   1. (i) Days of service credited to an employee on account of a payment which is calculated on the basis of units of time, such as days, weeks or months, shall be credited to the computation period or computation periods in which the period during which no duties are performed occurs, beginning with the first unit of time to which the payment relates.
   2. (ii) Days of service credited to an employee by reason of a payment which is not calculated on the basis of units of time shall be credited to the computation period in which the period during which no duties are performed occurs, or if the period during which no duties are performed extends beyond one computation period, such hours of service shall be allocated between not more than the first two computation periods on any reasonable basis which is consistently applied with respect to all employees within the same job classifications, reasonably defined.
3. (3) Except as provided in paragraph (c)(4) of this section, days of service described in paragraph (a)(3) of this section shall be credited to the computation period or periods to which the award or agreement for back pay pertains, rather than to the computation period in which the award, agreement or payment is made.
4. (4) In the case of days of service to be credited to an employee in connection with a period of no more than 31 days which extends beyond one computation period, all such days of service may be credited to the first computation period or the second computation period. Crediting of days of service under this paragraph must be done consistently with respect to all employees with the same job classifications, reasonably defined.