Vivir al día

Vivir al día
 

How do we say this expression in English?
It means that people like spending all the money they earn, not saving anything.

In Mexico it means that one earns so little money that one cannot actually save anything for the future. :)

To live "from day to day" is what I have heard

what about live from paycheck to paycheck

Sure, that works, but only if one has a paying job - which is sadly not the case these days for many people. Another option could be "to live from hand to mouth" since that implies having only enough for the moment.

Yes, that's the expression given by my dictionary, and widely used at least in the UK.

This is the most common phrase. Even though not everyone gets a paycheck, it still is the most common way in the US to express the idea that they spend everything they make.

You could say "living day to day" as well. This is even more severe. It is really a hierarchy.

Living month to month.
Living paycheck to paycheck.
Living day to day.

I think "living day to day" risks being understood as fighting severe depression or drug withdrawal.

The definition here isn't the same as the meaning of the Spanish saying.

I agree that this is a good equivalent of the saying.

I think both meanings are used in Spain.

If both meanings are used in Spain, then two different English equivalents are needed.

For the first meaning, written by the OP, we have:
live for today - live in the present
live for the moment - live in the moment - live in the now
live like there's no tomorrow - live today as if it were your last

For the second meaning, all the comments already given suffice.

That's true. It isn't as clear as paycheck to paycheck, since day to day could be in regards to many other things such as an illness or depression as you mentioned.