Annual Investment Allowance (AIA)

If you grew up in a very peculiar household...say, if Alex P. Keaton was your dad (if you're older than 35, just look it up)...your parents might have given you an investment allowance along with your lunch money. For the rest of us, the AIA is a specific provision of the British tax code that allows businesses to deduct a certain amount spent towards capital improvement.

Basically, if a company spends money to buy new equipment to improve its business, the U.K. government allows at least a part of that expenditure to be tax deductible. The amount is known as the annual investment allowance.