永久邮票，又称无面值邮票（英语：Non-denominated postage）是一种特殊邮票。所谓“永久”，是指其实际价值随着邮资的调整而变化。

永久邮票不印面值，而售价以当时第一类邮件资费为准。例如，某地第一类邮件资费为1美元，此邮票的售价即为1美元；当费率提高到1.5美元时，该邮票的售价也将上涨到1.5美元，但先前以1美元购买的邮票依然可以继续正常使用。

永久邮票大多等值于本地基本邮资，而美国于2013年开始发行的一套“Global”主题国际邮资永久邮票，则适用于寄往全世界的不超过1盎司（约28g）的普通信件（寄往加拿大则放宽到2盎司）。

Non-denominated postage is postage intended to meet a certain postage rate that retains full validity for that intended postage rate even after the rate is increased. It does not show a monetary value, or denomination, on the face. In many English-speaking countries, it is called non-value indicator (NVI) postage. Invented to reduce the cost of printing large issues of low-value stamps to "top-up" old issues, NVI stamps are used worldwide, including in the United States and some European countries.