Designed for 4-Up Box W2 Forms – Our W2 envelopes 4 UP sized specifically for 4-up W2 forms in a box layout, compatible with QuickBooks and other accounting software platforms. Dual Window Alignment – Pre-aligned Double Window Envelopes show only the recipient and return addresses without revealing sensitive tax information. Enhanced Security Tint – Black interior pattern protects confidential data and social security numbers during mailing. Peel & Seal Closure – Self-sealing flap with strong adhesive provides a secure seal—no tape or moisture needed. Premium Look and Durability – Constructed from sturdy 24 lb white wove paper for reliable mailing and a clean, professional appearance. Easily mail your 2025 W2 tax forms with these Blue Summit Supplies envelopes made for 4-up box W2 forms. This 100-pack offers precise compatibility with printed forms from QuickBooks and other tax software, featuring perfectly aligned double windows that display only the recipient and return addresses. Each envelope includes a peel & seal flap for quick closure and a black security tint to shield personal and financial details. Made with durable 24 lb white wove paper, these envelopes ensure your forms arrive intact and presentable. Note: These envelopes are designed exclusively for 4-up box W2 forms and are not compatible with 3-up, 2-up, or 1099 formats.