Why is a single-column resume considered the safest layout for ATS?

Because its reading order is obvious. In a single-column resume, text runs from top to bottom in one stream, so the order it is stored in the file matches the order a person reads it. Parsers then see each section heading followed by its content, and each job's title, employer and dates together, which makes it easier to fill fields correctly.

A single column also helps human readers:

• It works well on phone screens and in portal previews.
• It prints cleanly.
• It keeps the most important information, your recent experience, in the centre of attention.

Single-column does not have to look plain. You can use a strong name header, a coloured heading style, clear spacing and bold job titles. Many people use a full-width header with name and contact details, followed by a one-column body; this combines a modern look with low risk.

If you are unsure what layout to use for online applications, single-column is the reliable default. You can still test any design with the copy-and-paste test before applying.