Brendan Fraser needs USA to start airing "Encino Man" more often ... because his expenses outweigh his income by so much ... he's in the red each month to the tune of $87,320.01 ... TMZ has learned.

Fraser filed docs in Connecticut recently as part of an ongoing battle with his ex-wife to lower his alimony payments, which currently sit at $50,000/month. To prove his financial situation ain't what it used to be, Fraser listed his monthly income and expenses .... and it's not pretty.

According to Fraser, he makes about $205,704.04/month, but $112,803.25 goes to professional expenses -- DAMN YOU, AGENTS!!! -- leaving him with $92,900.79. 

Fraser says he makes another $25,800.28 from interest and other financial things rich people get ... and then the expenses kick in, including ... 

Alimony -- $50,000 
Mortgages -- $5,000+
Property tax -- $6,000+
Income tax -- $34,132.52
Child support -- $25,000
Gardening -- $5,200
Various insurances -- $5,000+
Family support and gifts -- $5,000+
Staffing -- $3,000
Pet care -- $7.77 (Does he have a goldfish?)
And it goes on and on ...

All told, Fraser's expenses have him losing $87,320.01/month. But Fraser's assets reportedly total just a shade under $25 million ... so we think he'll be fine.

But just in case, rent "Monkeybone" this weekend. Help a guy out, will ya?