Development Threshold
The development threshold defines an income threshold below which an individual's income, whatever country they may reside in, is taken to be exempt from the calculation of national fair shares. Which is to say that income below the development threshold is not taken to contribute to national capacity, nor are emissions corresponding to consumption below this threshold taken to contribute to national responsibility.
This threshold can be set between $0 and $20,000 per person per year (in Purchasing Power Parity terms). For reference, a development threshold of $7,500 PPP per person per year, which is a bit above a reasonably-defined global poverty line based on empirical observations, is the standard setting presented to the user.
Lower settings can be informative, but very low settings are difficult to justify as equitable. Countries like India, which are home to large populations of very poor people, are considered to have much more capacity when the development threshold is set to $0 than when it is set to $7,500, but this is only evidence of the problematic nature of such settings. Think of income tax systems, and consider that developed countries almost universally “exempt” extremely poor people from their tax bases. Very low development thresholds are inconsistent with the conventional progressive approach that virtually all societies have adopted for the purpose of income taxation, and they are difficult (if not impossible) to justify in equity terms.
See also Luxury Threshold.