Healthcare patient AR reserve: contractual allowances methodology

Develop a reserve methodology for patient accounts receivable for {provider_name}.

Inputs:
- Patient AR aging: {patient_ar_aging}
- Payer mix and contract terms: {payer_mix_terms}
- Historical collections by payer: {historical_collections}
- Denials and write-off data: {denials_writeoffs}
- Policy on charity care: {charity_policy}

Output:
1) Reserve methodology narrative (contractual allowances + bad debt).
2) Calculation tables by payer and aging bucket.
3) Sensitivity and reasonableness checks.
4) Journal entry recommendation and documentation checklist.

Be careful with assumptions; request missing payer data explicitly.