Being offered a promotion is always incredibly flattering, because it shows your employer has faith in your abilities and potential. Sometimes, however, you might want to turn the offer down. Now and then there are good reasons to turn down a promotion, and doing so is neither offensive nor an obstacle to you forging a successful career.
It may simply be that the timing isn't right. We've all got commitments outside of work, including young children or elderly parents in need of care. The extra responsibility and workload might be too much on top of that.
As to responsibilities, it may be that the new role just comes with far too many of them. If you're already stressed at work, you don't need any more pressure.
You might also turn down a promotion if it involves relocation. Taking a partner away from their job or pulling children out of school is not an easy decision, so considering the effect on others might make you pull back.
If the job you're being offered is a 'revolving door' with high churn, you have to wonder why nobody sticks at it. If other people couldn't make it work or didn't enjoy it, what's to say you will?
Finally, it may take you away from a job you love. We spend a significant portion of our lives at work, and if you're already doing something you enjoy, then you have to wonder if a change would be worth it.
Not all promotions are worth having, so think carefully before you decide whether or not to accept.
The timing isn't right
There are too many responsibilities
You are reluctant to relocate
The job is a 'revolving door'
You already love what you do