May I pay "in cash" or just "cash" without in?

What is the right phrase - May I pay "in cash" or may I "pay cash"?

Solution 1:

There seems to be an entire family of expressions involving pay + [form of money] that permit English speakers to use either "pay [form of money]" or "pay in [form of money]." For example:

pay cash & pay in cash

pay hard currency & pay in hard currency

pay dollars & pay in dollars

pay ready money & pay in ready money

pay silver & pay in silver

The dual acceptability seems to break down in situations where English speakers would normally use by in place of in. For example:

pay by check/cheque but not pay check/cheque

pay by credit card but not pay credit card

Members of the first set of phrases remain idiomatically acceptable (in U.S. English, anyway) when you substitute with for in:

pay with cash

pay with hard currency

pay with dollars

pay with ready money

pay with silver

In contrast, substituting with for in in the second group works only if you add an indefinite article after with:

pay with a check/cheque

pay with a credit card

The underlying distinction at work here may be the difference between form of payment (cash, hard currency, dollars, etc.) and mode of transfer (check/cheque, credit card).