I had been denied entry, deported and banned for 10 years from South Africa in 2016. The reason was that I hold a fraudulent work permit. Then in my home country I have applied for new passport. But the old passport number is written in the new passport. Now my wife is working in UK and I want to join her as a dependent. Will I get UK dependent visa based on my history? Will the UK officials track down my old passport history and deny granting me visa?
Yes, this will definitely affect negatively your chances of getting a UK visa.
The visa application asks you about previous deportations and refusals, so you will need to tell the UK authorities about it. If you do not do so, that is considered fraud and will attract an effective ban from the UK as well as South Africa. And yes, it is extremely likely that the UK will find out about your deportation whether you tell them or not. This is true whether or not they know your old passport number. Even in the unlikely event that they do not, if they were to grant you a visa, and then find out that you had lied on the application, that is grounds for later revoking the visa and possibly arrest and deportation.
Your chances of getting a visa are slim. From the UK's point of view you have already shown that you are prepared to lie and cheat in order to enter a country. Why should they believe that you will behave differently in the UK? However in the end it is a decision that the visa officer will make.
We cannot know how the UK will decide.
- Fraud is a very bad thing on your record; if you lied then, why should people believe you now?
- Trying to conceal the deportation is a very bad idea. So far you lied to South African officials, but the UK will take lies to an UK official much more seriously.
- You are not trying to enter for work, you are trying to enter to be with your wife. She has a job, a residence permit, and presumably your marriage is genuine.