I'm looking at purchasing a home and am trying to calculate affordability. I've created a Google spreadsheet which calculates my monthly mortgage commitments based on different input values (essentially different mortgage providers) and spits out a number but I want to take this one step further to determine if / how much by I need to increase my income.
I'm of the understanding that mortgage providers want to see proof of income that shows your monthly take home is at least double the monthly commitment. So I would like to calculate this from my calculated monthly mortgage estimates. However, I would like to know the required gross annual salary, not the net annual salary.
If I know the monthly take home figure, how can I calculate the gross salary taking into account the UK tax system (Just the normal PAYE, no special tax circumstances)?