Imports name this capability’s declared dependencies, which fune builds next to it in your project; each one links to its page.
import re
from .construction_cis_deduction_data import CIS_RATES, CIS_RATES_HISTORY ← this capability’s own data, compiled from data/cis-rates.json into the same file by fune build
from .construction_cis_deduction_types import CisDeduction, CisStatus
from .math_round_div import RoundingMode ← from math.round-div ^1.0.0 · built alongside by fune
from .money_add import subtract_money ← from money.add ^1.0.0 · built alongside by fune
from .money_amount import Money ← from money.amount ^1.0.0 · built alongside by fune
from .money_apply_rate import apply_rate ← from money.apply-rate ^1.0.0 · built alongside by fune
ISO_DATE = re.compile(r"[0-9]{4}-[0-9]{2}-[0-9]{2}")
def _rate_on(status: str, on_date: str) -> int:
best = None
earliest = None
for rule in CIS_RATES:
if rule.status != status:
continue
if earliest is None or rule.valid_from < earliest:
earliest = rule.valid_from
if on_date < rule.valid_from:
continue
if rule.valid_to is not None and on_date > rule.valid_to:
continue
if best is None or rule.valid_from > best.valid_from:
best = rule
if best is not None:
return best.basis_points
# A history=current build has dropped the old rows; say so rather than
# answering an old payment at today's rate.
if CIS_RATES_HISTORY != "full" and earliest is not None and on_date < earliest:
raise ValueError(
"no CIS rate for %s on %s: this build was installed with history=%s, "
"so it only carries rates from %s. Reinstall with history=full for older payments."
% (status, on_date, CIS_RATES_HISTORY, earliest)
)
raise ValueError("no CIS rate for %s on %s" % (status, on_date))
def cis_deduction(payment: Money, materials: Money, status: CisStatus, on_date: str, mode: RoundingMode) -> CisDeduction:
"""The CIS deduction a contractor withholds from a subcontractor's payment.
The rate applies only to the labour: VAT is left out by taking the payment
net of VAT, and materials (with consumables, non-travel fuel, plant hire and
prefabricated materials) are taken off before the rate is applied. Applying
20% to the whole invoice is the classic over-deduction.
"""
if status not in ("gross", "standard", "higher"):
raise ValueError('unknown CIS status "%s"' % (status,))
if not isinstance(on_date, str) or not ISO_DATE.fullmatch(on_date):
raise ValueError('onDate must be an ISO date (YYYY-MM-DD), received "%s"' % (on_date,))
if payment.minor < 0:
raise ValueError("payment must not be negative, received %d" % (payment.minor,))
if materials.minor < 0:
raise ValueError("materials must not be negative, received %d" % (materials.minor,))
labour = subtract_money(payment, materials)
if labour.minor < 0:
raise ValueError("materials (%d) cannot exceed the payment (%d)" % (materials.minor, payment.minor))
basis_points = _rate_on(status, on_date)
deduction = apply_rate(labour, basis_points, mode)
return CisDeduction(
payment=payment,
materials=materials,
labour=labour,
basis_points=basis_points,
deduction=deduction,
net_payment=subtract_money(payment, deduction),
)