Is there any good way to refuse to do something your boss asks? Actually, there are several.
Step 1: Begin your “no” with “yes” Frame your responses so that the first word your boss hears is 'yes,' not 'no.' For example, 'Yes, I'd love to be a part of that project. Unfortunately, another client is taking up all my time.'
TIP: Frame your refusal as 'it's not possible,' as opposed to 'I can't,' so it sounds like the reasons are beyond your control.
Step 2: Watch your body language Let your body language help convey the message of 'yes' even when you're saying 'no.' Keep your arms loose and open, and angle your body and feet toward your boss so you come across as pleasant and sincere, not annoyed and defensive.
Step 3: Have a good reason Come up with a good reason why it's in the boss's best interest to let you decline, like there is a specific project or duty that will suffer if you take this on.
TIP: 'It's not part of my job' is not a good reason to refuse a work assignment, unless you're being asked to do something completely inappropriate.
Step 4: Offer an alternative If no one cares that you're swamped, move to Plan B. Offer a specific alternative, like having an up-and-coming colleague take the reins, with you overseeing.
Step 5: Make amends Take the sting out of your refusal by following up with a concession: 'I'm really sorry that it's not possible for me to stay late tonight. But I'll cancel my plans for the rest of the week to see that this gets done.' Who can be angry at that?
FACT: A self-proclaimed atheist took action against a Wal-Mart in Portland, Maine, for firing him after he refused to fill in as the store Santa Claus.