EXCLUSIVE

Jeremy Renner's a deadbeat dad who refuses to pay for preschool and catch up on child support ... or so claims his ex-wife.

Sonni Pacheco says Jeremy time and again refuses to pay his half of the $1,600 monthly preschool tuition for their 3-year-old daughter, Ava. In new docs, obtained by TMZ, Sonni also says Renner's fallen behind on child support to the tune of $48,367.

As we reported ... Jeremy and Sonni struck a deal last year for Jeremy to pay $13k a month in child support as part of their divorce settlement -- and he seems to think that should be more than enough dough.

Sonni's docs include a text exchange where Jeremy says, "I'm not sure why you keep coming after more money here Sonni. I don't have the cash to give you. I'm sorry you can't figure out how to care for [Ava] with over 300k."