It's the question you hope will never arise during your job interview: What is your current salary?

Answer honestly, and you risk getting low-balled and missing your chance to climb the pay scale. Bend the truth, and you might overshoot the mark or, worse still, be found out as a liar.

In the U.S., the once routine query is becoming increasingly uncommon as a number of states, cities and companies have moved to ban it. New York City, Delaware, Amazon and Facebook are but a few of the places to make the shift away from the question.

The move is part of efforts to reduce the gender pay gap. Research suggests that salary history questions can cause pay disparities between men and women to snowball over time.

In some cases, the ban appears to be working. New York City-based recruitment specialist Oliver Cooke told CNBC Make It that one female candidate who interviewed through his firm secured a 100 percent pay increase shortly after the city-wide regulation came into effect.

"I'm pretty confident that if she had said her salary history she would have been offered much less," remarked Cooke, who said he had seen a "big shift" in the year since the roll out.

Yet, elsewhere, the question continues to rear its head. According to compensation research firm PayScale, 43 percent of U.S. workers are still asked about their salary history. Meanwhile, in other countries, the request is still widespread.

So, how should you respond to make the most of your next job opportunity?