240 days rule for visa extension

My company A has filed for h1B visa extension around mid June which was due to expire end of june. USCIS updates and articles suggests that its taking too long to respond and some blogs suggesting that when h1b extension is filed we can work for 240 days without any issue as long as the case is pending with USCIS. What if it does not come before 240 days? Will i be working illegally? Are the 240 days, calendar days/working days? Any more information will be appreciated.

I suggest you upgrade your petition to premium processing asap to be on safer side.

Generally they are calendar days.

Agree w/ ramanan256. You should get it upgraded to PP if you start getting close to 240 day threshold. 240 day window starts from I-94 expiration date.