Validate PolicyEngine child poverty estimates against RF/OBR benchmarks

[MaxGhenis]

Summary

The Resolution Foundation and OBR have published specific child poverty estimates for the November 2025 Autumn Budget. We should validate PolicyEngine's estimates against these benchmarks.

Target Benchmarks

Two-Child Limit Removal

Source	Children lifted from poverty	Cost (2029-30)
OBR	450,000	£3.0 billion
Resolution Foundation	480,000	£3.5 billion
PolicyEngine	TBD	TBD

Baseline Child Poverty

Source	2024-25	2029-30 (no action)
RF	31% (4.5m children)	34% (4.8m children)
PolicyEngine	TBD	TBD

Methodology Differences to Consider

1. Nowcasting: RF uses FRS with ONS price index nowcasting
2. Earnings growth: RF uses Bank of England/OBR wage forecasts with spillover effects
3. Housing costs: RF uses ONS PIPR for rent inflation
4. Take-up assumptions: Different benefit take-up rate assumptions

Tasks

• Run PolicyEngine simulation for two-child limit removal
• Compare fiscal cost estimates with OBR Table 3.2
• Compare child poverty reduction with RF/OBR estimates
• Document any significant discrepancies and their likely causes
• Update documentation if methodology adjustments are needed

Related Issues

• Add page to documentation on differences between our nowcasting and RF's nowcasting #1171 - PE vs RF nowcasting documentation
• Add RF methodology for earnings growth #1179 - RF earnings growth methodology
• Remove universal credit two-child limit (November 2025 Autumn Budget) #1388 - Two-child limit removal implementation

Source

• Resolution Foundation "No half measures": https://www.resolutionfoundation.org/publications/no-half-measures/
• OBR EFO November 2025, Chapter 3

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