Can I get multiple Chase Ink cards (and multiple sign-up bonuses) for signing up each of my companies with separate TINs, but associated with the same SSN of the me as owner of each?

you can try but, NO multiple bonus points are allowed, and they will deny all but one associated with your SS#... it doesnt matter how many EIN's or how many different named companies you have, it all comes back to your SS#

Odd that they allow multiple indvs to apply for separate accounts for the same business, yet don't allow separate businesses owned by the same person to have separate accounts. Bookkeeping would be horrendous if you had to use same card for 2 businesses.

I have 2 different Chase Ink cards and the 2nd one received a $400 first spend bonus (first one also had a sign on bonus). The thing about the Ink branded cards is that each flavor has different benefits so in theory a business owner might have a reason to apply for more than one type of Ink.

My Ink accounts were opened years apart so don't know if this has anything to do with it. The original card was formerly known as "Chase Professional" was opened long before the Ink program existed and is the 3% on gas, restaurant, office, home. I inquired a few times with CS about converting this card to the 5% cash back on telecom/office and was shot down each time.

I really wanted the 5% card (telecom is a big expense for me!) and so I finally bit on a targeted snail mail offer for 40K UR points on the first purchase. I was approved and got the 2nd sign up bonus.

Of course, YMMV but it is possible.

PS: IME Chase will deny a second bonus on any application that is an exact duplicate (ie straight churn).