9a reflects your proportionate share of the partnership's long term capital gains taxable to you. this increases your tax basis (just like a capital contribution). for a partnership K-1, distributions are shown in box 19 so i don't know what your talking about when you say box 20. if truly info in box 20 please provide letter and description and post back in this thread, so it can be explained .
distributions reduce your tax basis or another way to look at them is return of your capital contributions and income earned
the is no requirement in the tax laws for partnerships to make distributions of their taxable income.
there may be some provision in the partnership agreement abut distributions.
what I'm saying is you can get taxed on income you don't receive as cash currently and may not receive for years.
if this is a publicly traded partnership (box d checked) go the its website and see if allows access to the agreement. if not you can always contact their investor relations center
