Acting swiftly in declining a job offer ideally within 24 to 48 hours of receiving it is crucial. You can simply say, I found a position that I believe will offer me more opportunities to advance.A smart HR person can read between the lines. 1. Let your employer know as soon as possible. Tell them you appreciate their offer and are glad they picked you for the job. To avoid burning bridges with the new employer, you could have a discussion with them. In such cases, rejecting a job offer via email would be better. Keep the message short and ensure it's polite and professional. Use these sample letters for declining a job offer as a starting point to fill in your details. We hope this summary will make it easier to find specific areas of the book.