Subcontractor Payment Tracker
Business Case
Problem Statement
Subcontractor payments require careful management:
- Complex payment schedules
- Lien waiver tracking
- Compliance documentation
- Cash flow coordination
Solution
Comprehensive subcontractor payment tracking with lien waiver management, compliance monitoring, and payment scheduling.
Technical Implementation
import pandas as pd
from datetime import datetime, date, timedelta
from typing import Dict, Any, List, Optional
from dataclasses import dataclass, field
from enum import Enum
class PaymentStatus(Enum):
SCHEDULED = "scheduled"
INVOICED = "invoiced"
APPROVED = "approved"
PAID = "paid"
HELD = "held"
DISPUTED = "disputed"
class WaiverType(Enum):
CONDITIONAL_PROGRESS = "conditional_progress"
UNCONDITIONAL_PROGRESS = "unconditional_progress"
CONDITIONAL_FINAL = "conditional_final"
UNCONDITIONAL_FINAL = "unconditional_final"
@dataclass
class LienWaiver:
waiver_id: str
waiver_type: WaiverType
through_date: date
amount: float
received_date: Optional[date]
file_path: str = ""
@dataclass
class SubcontractorPayment:
payment_id: str
subcontractor_id: str
invoice_number: str
invoice_date: date
amount: float
retention_held: float
status: PaymentStatus
scheduled_date: date
paid_date: Optional[date] = None
check_number: str = ""
lien_waiver: Optional[LienWaiver] = None
notes: str = ""
@dataclass
class Subcontractor:
sub_id: str
company_name: str
contact_name: str
email: str
phone: str
contract_amount: float
retention_percent: float
trade: str
payments: List[SubcontractorPayment] = field(default_factory=list)
insurance_expiry: Optional[date] = None
license_number: str = ""
@property
def total_paid(self) -> float:
return sum(p.amount for p in self.payments if p.status == PaymentStatus.PAID)
@property
def total_retention(self) -> float:
return sum(p.retention_held for p in self.payments)
@property
def balance_remaining(self) -> float:
return self.contract_amount - self.total_paid - self.total_retention
class SubcontractorPaymentTracker:
"""Track subcontractor payments and compliance."""
def __init__(self, project_name: str):
self.project_name = project_name
self.subcontractors: Dict[str, Subcontractor] = {}
self._payment_counter = 0
def add_subcontractor(self, company_name: str, contact_name: str, email: str,
phone: str, contract_amount: float, trade: str,
retention_percent: float = 0.10) -> Subcontractor:
sub_id = f"SUB-{len(self.subcontractors) + 1:03d}"
sub = Subcontractor(
sub_id=sub_id,
company_name=company_name,
contact_name=contact_name,
email=email,
phone=phone,
contract_amount=contract_amount,
retention_percent=retention_percent,
trade=trade
)
self.subcontractors[sub_id] = sub
return sub
def record_invoice(self, sub_id: str, invoice_number: str, invoice_date: date,
gross_amount: float, scheduled_date: date = None) -> SubcontractorPayment:
if sub_id not in self.subcontractors:
raise ValueError(f"Subcontractor {sub_id} not found")
sub = self.subcontractors[sub_id]
self._payment_counter += 1
retention = gross_amount * sub.retention_percent
net_amount = gross_amount - retention
payment = SubcontractorPayment(
payment_id=f"PAY-{self._payment_counter:05d}",
subcontractor_id=sub_id,
invoice_number=invoice_number,
invoice_date=invoice_date,
amount=net_amount,
retention_held=retention,
status=PaymentStatus.INVOICED,
scheduled_date=scheduled_date or invoice_date + timedelta(days=30)
)
sub.payments.append(payment)
return payment
def approve_payment(self, payment_id: str, sub_id: str):
sub = self.subcontractors.get(sub_id)
if not sub:
return
for payment in sub.payments:
if payment.payment_id == payment_id:
payment.status = PaymentStatus.APPROVED
break
def record_payment(self, payment_id: str, sub_id: str, check_number: str,
paid_date: date = None):
sub = self.subcontractors.get(sub_id)
if not sub:
return
for payment in sub.payments:
if payment.payment_id == payment_id:
payment.status = PaymentStatus.PAID
payment.paid_date = paid_date or date.today()
payment.check_number = check_number
break
def attach_lien_waiver(self, payment_id: str, sub_id: str, waiver_type: WaiverType,
through_date: date, amount: float, received_date: date = None):
sub = self.subcontractors.get(sub_id)
if not sub:
return
for payment in sub.payments:
if payment.payment_id == payment_id:
waiver = LienWaiver(
waiver_id=f"LW-{payment_id}",
waiver_type=waiver_type,
through_date=through_date,
amount=amount,
received_date=received_date or date.today()
)
payment.lien_waiver = waiver
break
def get_pending_payments(self) -> List[Dict[str, Any]]:
pending = []
for sub in self.subcontractors.values():
for payment in sub.payments:
if payment.status in [PaymentStatus.INVOICED, PaymentStatus.APPROVED]:
pending.append({
'payment_id': payment.payment_id,
'subcontractor': sub.company_name,
'invoice': payment.invoice_number,
'amount': payment.amount,
'scheduled': payment.scheduled_date,
'status': payment.status.value,
'has_waiver': payment.lien_waiver is not None
})
return sorted(pending, key=lambda x: x['scheduled'])
def get_missing_waivers(self) -> List[Dict[str, Any]]:
missing = []
for sub in self.subcontractors.values():
for payment in sub.payments:
if payment.status == PaymentStatus.PAID and not payment.lien_waiver:
missing.append({
'subcontractor': sub.company_name,
'payment_id': payment.payment_id,
'amount': payment.amount,
'paid_date': payment.paid_date
})
return missing
def get_summary(self) -> Dict[str, Any]:
total_contract = sum(s.contract_amount for s in self.subcontractors.values())
total_paid = sum(s.total_paid for s in self.subcontractors.values())
total_retention = sum(s.total_retention for s in self.subcontractors.values())
return {
'project': self.project_name,
'total_subcontractors': len(self.subcontractors),
'total_contract_value': total_contract,
'total_paid': total_paid,
'total_retention_held': total_retention,
'remaining_to_pay': total_contract - total_paid - total_retention,
'pending_payments': len(self.get_pending_payments()),
'missing_waivers': len(self.get_missing_waivers())
}
def export_report(self, output_path: str):
with pd.ExcelWriter(output_path, engine='openpyxl') as writer:
# Summary by subcontractor
sub_data = [{
'ID': s.sub_id,
'Company': s.company_name,
'Trade': s.trade,
'Contract': s.contract_amount,
'Paid': s.total_paid,
'Retention': s.total_retention,
'Balance': s.balance_remaining
} for s in self.subcontractors.values()]
pd.DataFrame(sub_data).to_excel(writer, sheet_name='Subcontractors', index=False)
# All payments
pay_data = []
for sub in self.subcontractors.values():
for p in sub.payments:
pay_data.append({
'Payment ID': p.payment_id,
'Subcontractor': sub.company_name,
'Invoice': p.invoice_number,
'Amount': p.amount,
'Retention': p.retention_held,
'Status': p.status.value,
'Scheduled': p.scheduled_date,
'Paid': p.paid_date,
'Waiver': p.lien_waiver.waiver_type.value if p.lien_waiver else 'Missing'
})
if pay_data:
pd.DataFrame(pay_data).to_excel(writer, sheet_name='Payments', index=False)
return output_pathQuick Start
tracker = SubcontractorPaymentTracker("Office Tower")
# Add subcontractor
sub = tracker.add_subcontractor(
company_name="ABC Electrical",
contact_name="John Smith",
email="john@abcelectric.com",
phone="555-1234",
contract_amount=500000,
trade="Electrical"
)
# Record invoice
payment = tracker.record_invoice(sub.sub_id, "INV-001", date.today(), 50000)
# Approve and pay
tracker.approve_payment(payment.payment_id, sub.sub_id)
tracker.record_payment(payment.payment_id, sub.sub_id, "CHK-12345")
# Attach waiver
tracker.attach_lien_waiver(payment.payment_id, sub.sub_id,
WaiverType.UNCONDITIONAL_PROGRESS, date.today(), 50000)Resources
- DDC Book: Chapter 3.1 - Cost Management