Adams 1099-NEC Envelopes - Adams 1099 Envelopes are security-tinted for privacy and sized for a precise fit with tax forms with three forms per sheet like the 1099-NEC. Durable, gummed closure provides an aggressive seal. Complex security tint conceals the appearance of letters and numbers, even when held to light. Perfectly aligned double windows keep personally identifiable information out of view. Envelopes are designed to fit 1099-NEC tax forms.