be down to
US /bi daʊn tu/
UK /bi daʊn tu/

1.
to be the result of a particular thing
:
•
The success of the project was down to hard work and dedication.
•
Her poor performance was down to a lack of preparation.
2.
to be someone's responsibility
:
•
It's down to you to make sure everyone is informed.
•
The final decision is down to the manager.
3.
to have only a particular amount of something left
:
•
We're down to our last few dollars.
•
After all that work, we're down to the final two candidates.