I applied for a B1 visa to attend a conference in the USA in 2013. I had another nationality (Non- VWP) at the time and my B1 application rejected under section 306 of border security. I now can apply for ESTA under my new nationality. Can my ESTA application get approved? If not and I need to apply for visa is it every time I need to travel to stated or is it just the first time?
One of the questions you will be asked when applying for the ESTA is :
Have you ever been denied a U.S. visa or entry into the U.S. or had a U.S. visa canceled?
You will also need to provide details of where and when you were rejected.
The US CBP website has a question that covers your situation exactly. It states :
Many people make the mistake of thinking that if they were denied a visa when they were a citizen of one country, then become a citizen of another country, they can travel to the U.S. under the visa waiver program using their new passport. That is wrong. The eligibility question about having been denied a visa does not ask whether or not the denial was made after you became a citizen of another country. It asks, "Have you ever been denied a visa?" - period. If you answer "No" then we determine that you have been denied a visa in the past, we consider that to be fraud, and you will be barred from entry for a number of years. It is better to admit the truth, and then apply for a visa, than go through the experience of being deported for fraud.
Answering Yes will not necessarily cause your ESTA to be rejected, but there's a very high chance that it will. Regardless, it's worth going through the process of applying for an ESTA - even if the chances of it being rejected a high, the process is much easier than applying for a visa, and being rejected for an ESTA will NOT cause you any additional trouble (presuming of course that you don't lie on the application!)
Presuming your ESTA is rejected, you will need to apply for a B1 and/or B2 visa. These can be issued for multiple entries over multiple years, so you will not necessarily need to apply for a new one for each trip, but it is likely that you will need to have a visa for all future trips to the US rather than being able to use the ESTA, even after your B1/B2 has been approved.