When Reg E claims are opened is the date the claim is received considered day 1 or day 0 when "counting" calendar days for resolution timeframes.

Day 0

Thank you Rick. Do you know if this is addressed in the regulation itself or the commentary anywhere? I have been digging but have not been able to locate anything yet.

What specific timing are you referring too in Regulation E?

Looking specifically at 1005.11(c)(2) - If a error is reported on a Saturday does that day start the 45 day counter or would the counter start on Sunday and Saturday would be considered day 0?

Hope that makes sense, thank you for your guidance.

the institution may take up to 45 days from receipt of a notice of error to investigate and determine whether an error occurred.

It is spelled out in black and white with examples - no. But if I receive the notice of error today (Wednesday) and I investigate the error and determine that an error occurred tomorrow (Thursday), that occurred within one day from receipt and not two. The day of receipt is day zero.

You have to read and interpret the Reg. You have 10 business days to investigate your claim. Reg E defines a business day as a 24-hour period beginning at midnight. Therefore your first business day starts as your clock chimes 12 and (presumably) it's dark outside. If that is day 1, you got the claim on day 0.