Crossing border while H1-B is being processed

My H1-B is in the process of being filed, however the company wants me to start work on January 24. They are telling me as long as they provide me with a copy of the filing (or maybe it's the filing receipt, I forget the exact word they used), I will be able to cross the border and start working immediately.

I've only ever heard that you need the full, approved H1-B in order to cross/work. Has anyone heard of this kind of situation?

I'm just worried that I'll be denied at the border and told to come back once I have the actual visa, which would create huge problems ie. my moving truck that will already be en route to Arizona, with nowhere to drop my things off for two months until the visa comes through!

Unless you have previously had an H1, you cannot work nor enter US on H1 until it is approved.

Only those who previously held h1, then, indeed you can begin work immediately upon issuance of the receipt notice. That may be where the company is confused.

I agree with you. I recently went through the H1B process and as far as I know, there is no middle ground, like being able to start work and live in US until your visa is approved. In fact, when I went through customs before the visa was approved, they specifically told me that they would turn me back, even my moving company, if I don't have the visa stamped on my passport.
You might want to try contacting US citizenship and imigraion service (USCIS) for the official answer. their number (which works in canada too) is 1-800-375-5283. they have a lengthy set of telephone recording instructions. to speed things up, press 1 (for english), then 7 (for visa info), then 3 (for foreign nationals), then listen for customer service option.
lastly, in order to work in the US, you'll need a Social Security Card. However, you can't get one until your visa status is activated. Therefore, I don't see anyway you can start work.

in order to work in the US, you'll need a Social Security Card.

Not quite true. It is a hassle (for tax withholding purposes among otherthings) for the employer if you don't have the card, but your I-94 is your work authorization, and you can work while SSN is "pending".

-- Thu Jan 06, 2011 9:58 am --

In fact, when I went through customs before the visa was approved, they specifically told me that they would turn me back, even my moving company, if I don't have the visa stamped on my passport.

Just to clarify, if you get H1 approval (I-797 notce), as a Cdn, you show up at the border with this to get your I-94 and passport stamped. You do not get a "visa", which only would be issued at a consulate, and is never issued to Cdns.