Can I claim partnership expenses not claimed in my partnership return?

I had to dip into my own pocket to purchase partnership-related goods and services, due to the fledgling nature of the company and limited partnership working capital. Can I claim these on my joint personal tax return? I have read conflicting answers on what is able to be deducted from my personal return that relates to my business (partnership share of 33 1/3%)? Thanks in advance!

Thanks for the answers so far - one more important detail in response - there is no formal partnership agreement. However bank documents were signed and an account opened as 1/3 each. Does this imply a 33 1/3% partnership basis?

Nope, you must have them reimbursed by the partnership and then amend the partnership return if necessary. Otherwise it's treated as a capital contribution. You could take a partner draw for the amount with no tax consequences.

Unless your partnership agreement said in writing that you would pay for these items and wouldn't be reimbursed (highly unlikely!), then you made a capital contribution and the partnership would get the deduction.