Should I use the spelling (and punctuation) 'day-to-day', 'month-to-month', and 'year-to-year' or 'day to day', 'month to month', and 'year to year'?
closed as off-topic by Kristina Lopez, ScotM, Misti, Tushar Raj, Edwin Ashworth Jul 2 '15 at 10:36
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Please include the research you've done, or consider if your question suits our English Language Learners site better. Questions that can be answered using commonly-available references are off-topic." – Kristina Lopez, ScotM, Misti, Tushar Raj, Edwin Ashworth
Context is key.
You use hyphens when the compound words are really a single word that don't make sense by themselves. Suppose "month to month" modifies another word, as in:
My lease is up, so now I'm on the month-to-month portion of the contract.
You should hyphenate month-to-month because it becomes an indivisible adjective to describe portion. (You could not say, for example, * month portion of the contract or * month to portion of the contract. You could not say these because the compound words month-to-month are tied together in meaning.)
I'm eking out a meager day-to-day existence.
In contrast, for the sentence
I'm living from day to day.
no hyphens are needed, as there's no word being modified by day to day.
A helpful reference would be the Chicago Manual of Style, and their Table 6.1 ("A spelling guide for compound words.") I'm reading from the ancient and venerable 13th ed.