ADP Refund earnings calc question

When I am hand calculating earnings on an ADP refund, I usually take the gross amount of the refund, divide it by the amount of the contributions deposited in the year to get a factor.  Then multiply the factor times the earnings of the period to get the earnings on the refund.

For example, $5000 deferrals and $1000 refund.  Factor 20%.  earnings $500.  Refund earnings $100.

However, in this case, the participant is getting (nearly) all of her deferrals back (5800 out of 5850).

AND, not all of the deferrals were deposited during the year.  So, my factor is over 100%.  To cap it off, there was a zero balance to start the year.

So, I now have refund $5800, deposits $5000.  So my factor would be 116%.

My thinking is to use 5000 plus all the earnings plus the remainder of the deposit.  So, 5000 + 500 + 800 for a refund of 6130.

What do you think.  I've never dealt with this particular situation before.

I think you use total deferrals, not just those deposited during the year.  What if only $100 was deposited during the year?

I'd use 5800/5850 as the factor.