The IRS states that the 1099/1096 must be Red.
Whether or not they will accept forms that don't meet their specifications, I don't know, but their own rules say they must be red. Their rules also say there are penalties for filing them against their specifications. Here is what they say:
"All print on Copy A of Forms 1097-BTC, 1098, 1098-C, 1098-E, 1098-MA,
1098-Q, 1098-T, 1099-A, 1099-B, 1099-C, 1099-DIV, 1099-G, 1099-INT,
1099-K, 1099-MISC, 1099-OID, 1099-PATR, 1099-Q, 1099-R, 1099-S, 3921,
3922, 5498, and the print on Form 1096 above the statement, “Return this
entire page to the Internal Revenue Service. Photocopies are not acceptable.”
must be in Flint J-6983 red OCR dropout ink or an exact match. However, the
four-digit form identifying number must be in nonreflective carbon-based
black ink in OCR A font."
<a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-pdf/p1179.pdf#page=14">https://www.irs.gov/pub/irs-pdf/p1179.pdf#page=14...>
In most cases, it is easier to e-file them, rather than mail them.
