The order that was put into place to allow the deferral did not place a limit on the amount of the deferral. The order stated that the deferral applied to the 6.2% Social Security on the first $137,700 of wages. At the time, that amount was equal to the Social Security tax limit. However, not all employees were eligible to participate. Only those who earned less than $4,000 on a bi-weekly basis were eligible for the deferral. This amount was calculated on a pro-rata basis for employees who were paid on different schedules. So, you must earn less than $2,000 weekly or $4,333 bi-monthly. If you earned more than these amounts, then you were not eligible to participate in the tax deferral.
It should also be noted that you may be eligible during one pay period but not the next. For instance, if you got paid weekly and your salary was $1,750, you could defer your taxes. If your salary was $2,100 during the next pay period due to overtime, then you could not defer your taxes during that pay period. The deferrals were all-or-nothing as there were no pro-rata calculations to determine how close you were to the limit. If you made $1 over the limit, then you could not defer any of your Social Security tax during that time period.