This is plainly evident in the 2015 Family Income and Expenditure Survey (FIES), where the NCR towers above the rest of the country in terms of Median Income Per Capita: Php 313,000 for NCR vs. Php 180,000 for the entire Philippines.
But which region has the highest income inequality? One easy way to do that is by taking the ratio of the tenth decile (the top 10% in income) to the first decile (the bottom 10% in income).
From the 2015 FIES, we get this table...
|Median Income Per Capita (In Thousands of Pesos)|
|Region||Overall||Bottom 10%||Top 10%||Top/Bottom|
|Region I - Ilocos Region||173||99||553||558.59%|
|Region II - Cagayan Valley||168||98||557||568.37%|
|Region III - Central Luzon||223||103||614||596.12%|
|Region IVA - Calabarzon||234||106||711||670.75%|
|Region IVB - MIMAROPA||142||79||608||769.62%|
|Region V - Bicol Region||136||88||482||547.73%|
|Region VI - Western Visayas||149||87||523||601.15%|
|Region VII - Central Visayas||160||62||607||979.03%|
|Region VIII - Eastern Visayas||124||72||526||730.56%|
|Region IX - Zamboanga Peninsula||127||73||503||689.04%|
|Region X - Northern Mindanao||135||68||612||900.00%|
|Region XI - Davao Region||166||85||571||671.76%|
|Region XII - SOCSKSARGEN||123||56||495||883.93%|
|Region XIII - Caraga||134||74||544||735.14%|
and this chart:
Based on this, we can see that the region with the highest income inequality is actually Region VII - Central Visayas, composed of the three provinces of Bohol, Cebu, and Siquijor. In terms of overall income, this region is "middle of the road." Its median income per capita was only Php 160,000 in 2015, slightly lower than the Philippines median income per capita of Php 180,000. But, in Central Visayas, the top 10% earn almost 10 times the bottom, higher than the overall Philippine ratio of 7.85 times.
NCR was actually more egalitarian, wherein the richest 10% "only" earned 5.73 times the poorest 10%. Surprisingly, the most egalitarian region is also the poorest: ARMM, where the median per capita income is only Php 115,000 (around US$ 2,300). There, the richest 10% earn "only" around 3.11 times the poorest 10%.