Green’s Dictionary of Slang

(UK/US campus) to pay (for), to lend money.

1879		London Life 31 May 7/2: if you have plenty of ‘tin,’ (either your own or somebody else's, it don't matter a button), and don't mind ‘floating’ it, you may find [...] many a charmer as kind as desire might wish.
1969		A. Buzo Rooted I iii: I don’t suppose you could have a word to Simmo and ask him if he could perhaps ... float me a bit of a loan, could you?
1987		(con. 1981) G.W. Clemente Cops are Robbers 148: ‘ I had to float some dough to my pals down in Florida for helping me with my alibi’.
1997–2000		Da Bomb 🌐 11: Float: To lend; to pay for.
2004		J.A. Juarez Brotherhood of Corruption 261: ‘You’re straight. We’ll float ya the ducats if we see the guy’.