This MWE does not produce a zero margin page. The word "Test" is shifted about 0.5cm from the left.
\documentclass[10pt,letter,article]{memoir} \usepackage{geometry} \geometry{left=0in, right=0in, top=0in, bottom=0in} \begin{document} Test \end{document} The remaining margin in your test file is due to the indentation of the first paragraph. The following produces what you want:
\documentclass[10pt,letter,article]{memoir} \usepackage{geometry} \geometry{left=0in, right=0in, top=0in, bottom=0in} \begin{document} \noindent % no indent of the first line in this paragraph Test \end{document} If you don't want the indent of each first line of a paragraph, you might reduce the indentation to 0pt with \setlength{\parindent}{0pt}
