1) Under what visa category have you worked in the UK since finishing your course in July 2006? Have you overstayed/worked illegally?
2) Given that your query regards tax issues specific to Nigeria, you may find that it's better to work with an immigration lawyer who is familiar with applicants from Nigeria. However you may not be able to find one within the time you have left to submit your request for review.
3) Is there any way you can write a letter that explains to the caseworker step-by-step, in detail, how to use the evidence that you actually provided to come up with the required points? No whingeing, no moaning, no excuses, just, "My letter of refusal from [date] cites "[quote the actual words on your rejection letter]" as the reason(s) my HSMP visa application was refused. I dispute this reasoning on the grounds that I provided [whatever they say is lacking].
I included the following documents in my application materials to corroborate my earnings as stated within my HSMP 1 application form:
- . Here is an explanation of how the documents that I provided with my initial application serve to corroborate my claimed earnings of GBPXXXXX: [numbered steps, 1 through whatever]."
If it is true that your earnings from the period you are claiming cannot be verified using ONLY the evidence that you provided in the envelope with your initial application, there is no point applying for a review. If there's no way that your claimed earnings could be deduced from your available documents a review request is pointless. You should also consider whether you have worked illegally in the past year. Being an overstayer/illegal worker can be bad news when you go for EC or FLR. IF you have been on a work permit for the past year so you are not technically illegally working, continuing on that path until you have the points to switch to HSMP might be the most feasible option.
4) Now, bearing in mind that you most likely do not _want_ to go back to Nigeria for an extended period, the possibility of going there to work for a year and then qualifying for HSMP may be worth considering. If you could take your cool UK qualification back to Nigeria and make a load of money according to the tables set out in the HSMP Guidance, could you qualify for HSMP next year without excuses or extra explanations?