Send money / Request money
The person you are sending money to is the recipient of that money, but what would you call a person you are requesting money from? A requestee?
Solution 1:
Donor is a term that is corresponds to recipient, although it has connotations of not receiving goods or services in response.
Another approach is to name them after their role. Who normally pays money? customers and employers. A more general term is provider, but might equally apply to the recipient, assuming they are selling goods or services.
Another general term is sender, which would normally be matched with receiver.
Finally, tongue-in-cheek, who do you ask to send you money? Your mother.
Solution 2:
As dangph mentioned in the comments, it really depends on the context of why you're giving them the money.
If the person has no choice but to pay you, for example a ransom, or court fine, you would be the demander from freedictionary.com:
to ask for urgently or insistently: demanding better working conditions; claiming repayment of a debt; exacted obedience from the child; tax payments required by law.
If they were sending the money as a donation or payment, they could be a patron (emphasis mine) from reference.com:
- a person who is a customer, client, or paying guest, especially a regular one, of a store, hotel, or the like.
- a person who supports with money, gifts, efforts, or endorsement an artist, writer, museum, cause, charity, institution, special event, or the like: a patron of the arts; patrons of the annual Democratic dance.
Though you should be careful with this as patron usually implies the money was unsolicited.