(2) Facts-and-circumstances determination. Whether the timing of a plan amendment or series of plan amendments has the effect of discriminating significantly in favor of HCEs or former HCEs is determined at the time the plan amendment first becomes effective for purposes of section 401(a), based on all of the relevant facts and circumstances. These include, for example, the relative numbers of current and former HCEs and NHCEs affected by the plan amendment, the relative length of service of current and former HCEs and NHCEs, the length of time the plan or plan provision being amended has been in effect, and the turnover of employees prior to the plan amendment. In addition, the relevant facts and circumstances include the relative accrued benefits of current and former HCEs and NHCEs before and after the plan amendment and any additional benefits provided to current and former HCEs and NHCEs under other plans (including plans of other employers, if relevant). In the case of a plan amendment that provides additional benefits based on an employee's service prior to the amendment, the relevant facts and circumstances also include the benefits that employees and former employees who do not benefit under the amendment would have received had the plan, as amended, been in effect throughout the period on which the additional benefits are based.