How to cut corners of a rectangle like this?

[Mo23193221yoo2]

Is there a way to cut a rectangle's corners like this?

[Trevor.Dennis]

Create a square document.

Fill the background with black

Create a new layer and fill it with white

Use Free Transform to rotate the white layer 45°

[Semaphoric]

Using the same general idea, you could do this on any aspect ratio image by making a square selection centered on the image, and use Select > Transform Selection to rotate 45° and scale for the desired amount of cut, and then use the result as a Layer Mask.

[Jeff Arola]

If you use the Rectangle Tool to create a shape layer, then you can use this Corner Editor script

then Image>Trim.

https://photoshopscripts.wordpress.com/2015/07/29/corner-editor-update-for-photoshop-cc-2015/

[Nancy OShea]

This is what clipping masks are used for.  Use any shape you like -- super simple or complex custom shapes.  

In this example, I used a puzzle piece from the Custom Shape library with a solid fill and border.  Notice the Layers panel.