up to (one's) ears (in something)
Extremely busy (with something); deeply or overly involved (in something); possessing, filled up with, or overwhelmed by an excessive amount (of something). There's no way I can take a vacation right now, I'm up to my ears in work at the moment! I only meant to be peripherally involved in David's business venture, but before I knew it I was in up to my ears! Dana was worried she wouldn't find any work as an accountant working for herself, but she's up to her ears in clients!
up to your ears
If you are up to your ears in work or in an unpleasant situation, you are very busy with it or are deeply involved in it. I can't come out this evening — I'm up to my ears in reports. Trimarco's campaign director was said to be up to his ears in dirty business deals.