Estar endeudado hasta el cuello

[ROBINDESBOIS]

to owe a lot of money.
English?

[Rusty]

Look here (http://www.tomisimo.org/idioms/es/estar-metido-en-algo-hasta-el-cuello-3054.html) for some examples of the idiomatic expressions.

To be knee-deep in debt.
To be up to your eyes in debt.
To be in way over your head.