'DWTS' Pro Gleb Savchenko's Ex Reveals Modest Monthly Income In Custody War

'DWTS' pro Gleb Savchenko's ex-wife, Elena Samodanova, claims she only earned $3,846 last month before taxes ... and she says it's way less than she needs for her monthly expenses ... TMZ has learned.

According to new legal docs obtained by TMZ, Elena says that in the last 12 months, she's averaged $4,380 monthly income as an assistant studio manager at Phoenix Connect.

On top of her salary, Elena -- who is based in Hong Kong -- also reported an average monthly income of $1,873 from a rental property.

Meanwhile ... Elena lists her fiancé Vlad Kvartin's income as $3,500 a month ... and says that Gleb pays $2,273 in child support for their two children.

Elena says that she currently has more than $127,500 in debt from a house renovation loan and a line of credit for family living expenses combined.

She also claimed her total monthly expenses were $17,601.18 -- but says $3,000 of those expenses were paid by others.

Elena and Gleb are battling over custody of their daughter, Olivia. Meanwhile, Olivia's sister, Zlata, lives with Elena in Hong Kong.

As we reported ... Gleb has claimed that Elena and Vlad -- who welcomed daughter Victoria 10 months ago -- sent sexually explicit messages about Gleb to his Olivia, who lives with Gleb in Los Angeles.

In response ... Elena called these claims false and said he has "no proof."