Mailing Form 1120 + Form 5472: Why Wet Signature Is Mandatory (Not Just Recommended)

Wet Sign for Mail: The Safe Default

If you're going to mail the pro forma Form 1120 + Form 5472 (instead of faxing), the answer to "should I wet sign?" is yes. Always.

Mail is the most scrutinized delivery method. Unlike fax (where the IRS receives an image and may not distinguish wet from electronic signatures), mailed paper is examined as a physical document. A typed signature on a mailed form is immediately distinguishable from a hand-signed signature.

Why Fax Is Slightly More Forgiving

When you fax, the IRS receives a scanned image of whatever you sent. They can't always tell whether the signature was wet ink or a digital overlay — both look similar in the rasterized fax. So digital signatures are sometimes accepted on faxed filings, even though it's still not the safest approach.

But mail is different. The IRS receives the actual paper. A signature line filled with typed text is unmistakably non-wet. A printed digital signature image is detectable as printed. Wet ink is unique — and the only signature type unambiguously authentic on mailed paper.

The Procedure for Mailed Filings

For mail submissions:

1. Fill the form digitally in your PDF editor 2. Print all pages of the final package on standard paper (Form 1120, Form 5472, attachments) 3. Sign the Form 1120 signature line in BLACK INK with a regular pen 4. Date the signature 5. Sign the Form 5472 signature (Item 3 on Form 5472, where present) 6. Sign and date the §1.6038A-2 supplementary attachment 7. Assemble the signed pages in the correct order 8. Mail via DHL/FedEx/UPS (an IRS-approved private delivery service)

All three signatures (1120, 5472, attachment) should be wet — same pen, same person, consistent date. The IRS reviewer cross-references these and an inconsistent signature pattern looks suspicious.

Why "Wet Sign" Means Pen and Ink, Not a Wet Pen

The phrase "wet sign" is jargon that confuses non-native English speakers. It doesn't refer to literal wetness or any specific kind of ink. It means: a signature made with a physical writing instrument (typically pen) on physical paper, at the moment of signing.

Opposite of wet sign: any digital signature, typed name, scanned-and-pasted signature image, or stylus-on-screen signature. All of these are "electronic" signatures, even if they ultimately appear as ink-like marks on paper.

The Mailing Address (Reminder)

Mail to the specific Foreign-Owned DE address listed in the Form 5472 instructions — NOT the standard Form 1120 address. Using the wrong address sends your filing to the wrong unit, causing weeks of delay even if the signature and content are perfect.

The specific address rotates occasionally as the IRS reorganizes. Always cross-check with the current Form 5472 instructions on irs.gov before mailing.

Use a Black or Dark Blue Pen

Standard IRS guidance: use black or dark blue ink for signatures. Avoid red ink (visually associated with corrections, may confuse processors), light colors (low contrast on scanned documents), or unusual colors.

Black is the safest default. The signature should be clear, visible, and unmistakable as your authentic mark. Avoid gel pens with metallic ink, fountain pens with watery ink, or markers with too-thick lines.