Kelis' housekeeper claims the R&B singer owes her $900 in unpaid wages -- and according to sources, there's one major problem preventing her from seeking justice ... she's an illegal alien.

We're told Kelis' maid earned $150 a day for her work ... and since she only worked one day a week, that means Kelis somehow fell six weeks behind on her payments.
According to sources, the housekeeper is currently exploring her legal options -- trying to lock down a lawyer to see if she can file anything with the California Labor Commission.
As we previously reported, Kelis' rapper ex-husband
Nas has been ordered to pay her over $25,000 a month in child and spousal support. Not too shabby.
Calls to Kelis' camp haven't been returned.
Nas just had his child and spousal support obligations sliced in half, but he still has to pay ex-wife
Kelis a pretty penny ... TMZ has learned.

According to legal docs filed in L.A. County Superior Court, Nas must now pay a tad over $5,000 a month in child support and $20,000 a month in spousal support.
It sounds like a lot, but Nas was paying twice that until he convinced the judge the bad economy has even hit the rap biz hard.
So this month, Nas pockets an extra $25k for himself.
One love.
It's tough being a rapper trying to eke out a living with an ex-wife, a kid and an out-of-control mortgage ... but
Nas may have figured out a way to stay afloat.

TMZ obtained legal docs in which Nas concedes he owes
Kelis a skosh less than $300,000 in
spousal support. But it seems the most pressing problem is the mortgage for the home Kelis is living in -- Nas is behind $52,989.22.
So Nas' lawyer,
Mark Vincent Kaplan, filed a payment plan with the court, in which the rapper agrees to pay $17,500 up front, and then pretty much double the $7,800 mortgage payment each month to catch up.
It's pretty amazing -- Kelis' lawyer,
disso queen Laura Wasser, has claimed Nas raked in $244,826 a month.
According to the docs, the plan is to sell the home stat.

We got this photo of Kelis and her son, Knight, out in Hollywood yesterday.
Sometimes a picture is worth a thousand ... bucks.
After an eternity of legal war, the marriage between rapper
Nas and singer
Kelis is officially
kaput.

TMZ obtained legal docs, filed last Friday in L.A. County Superior Court, which show that the marriage has been terminated -- but there are still a few more nasty battles to fight ... like child custody and spousal support.
Currently, Nas is ordered
to fork over roughly 10k a month for child and spousal support -- which he claims
he can't afford.
So, the next round should be all sorts of fun.
Stay tuned.
Nas claims he can't afford to pay
Kelis the child and spousal support ordered by the court.
As we first reported, a court ordered
Nas last month to pay more than $87,000 in back spousal and child support. The judge also ordered Nas to pay
Kelis $10,000 a month in spousal support to stay current. It's unclear how much Nas is required to pay in monthly child support.
Nas says in the new legal docs obtained by TMZ ... the judge predicated the order on Nas making $152,031 a month, but the rapper says he makes "substantially less than that amount."
Nas' lawyer,
Mark Vincent Kaplan, is asking the judge to take another look at the damage to Nas' wallet.
Kelis wants to be legally divorced from
Nas so bad -- and so quick -- she has filed papers with the court asking them to make the split official ASAP.
According to documents filed last week, Kelis said in a declaration, "... it would be in the best interest of both of us if our marital status is terminated as soon as possible."
Because she fears that the legal proceedings could take years to figure out, Kelis has requested that the judge immediately terminate their marriage -- and wait until a later time to resolve "all other issues."
As for the odds that the two will rekindle their romance -- Kelis stated, "I believe there is no possibility of reconciliation with [Nas]."
Nas went to court Monday over his divorce with
Kelis -- and walked out a little lighter in the wallet.
According to documents filed in L.A. County Superior Court, Nas had to immediately fork over $47,249.42 in back child support and $40,454 in back spousal support.
The judge also ordered Nas to pay $10,000/month in spousal support until he pays off the $299,015.50 he owes Kelis.
Nas also has to pay 90% of Kelis' legal fees in the amount of $155,787.28.
Lastly, Nas has to pay $48,549.83 to cover Kelis' accounting expenses.
The lesson, as always -- when
Laura Wasser reps your ex, settle as quickly as possible. Nas just learned that the hard way.
Kelis just got smacked over a
$5,000 hair weave. Yes folks, 3 zeroes.
Kelis got the weave at a fancy schmancy Santa Monica
salon back in May 2009 but, according to legal docs, the singer never coughed up the dough.
This morning, the stylist showed up for the trial, but Kelis didn't ... so the judge entered a default judgment for the full amount.
No word if Kelis will ask for an extension from the court.

Rapper
Nas needs a wake-up call -- he's trying to win back his estranged baby mama
Kelis (despite the fact she's suing him over child support) and now he owes the IRS a huge chunk of change.
We told you about the tax lien the IRS slapped on Nas back in October to the tune of
$2,584,206.31. Now, according to court docs, Nas' bill has ballooned to a whopping $3,365,671.26. Not
Joe Francis territory, but getting close.
Last week, Nas was ordered to pay baby mama Kelis $200,000 in back child and spousal support.
Our sources say Nas doesn't have a clue he's going under financially and doesn't understand he can go to jail if he doesn't pay child support. He was at Sundance recently and raked in $50,000 for a performance, which, we're told, he blew before he blew out of Sundance.
And more news in the non-reality department -- Nas has been sending Kelis a flurry of emails, telling her how much he wants her back and where she can fly to hook up with him. Nas -- she has a new boyfriend and has moved on. She really wants that divorce.
Nas has just pled not guilty to contempt of court, in what has become a bitter divorce case between him and
Kelis.

In court this AM, Kelis' lawyer alleged Nas owes more than $200,000 in child and spousal support, along with attorney's fees.
Kelis' lawyer had filed a contempt motion earlier because her estranged hubby refused to pay up ... today, through Nas' attorney, the rapper pled not guilty.
A contempt hearing will be held next month. If convicted, Nas could go to jail.

Here's singer/Nas babymama
Kelis at an event Thursday night in L.A. (
left) ... and an old ad for
Artemia salina x nyos, A.K.A.
Sea Monkeys (
right).

One of 'em is popular with the boys in the yard.
We're just sayin'.