accountant-expert

SKILL.md

Accountant Expert

Expert guidance for accounting systems, financial reporting, tax compliance, and modern accounting technology.

Core Concepts

Accounting Principles

GAAP (Generally Accepted Accounting Principles)

IFRS (International Financial Reporting Standards)

Double-entry bookkeeping

Accrual vs cash accounting

Financial statement preparation

Audit and assurance

Financial Statements

Balance sheet (Statement of Financial Position)

Income statement (P&L)

Cash flow statement

Statement of changes in equity

Notes to financial statements

Tax & Compliance

Corporate tax planning

VAT/Sales tax management

Payroll tax compliance

Tax filing and reporting

Transfer pricing

International taxation

Double-Entry Bookkeeping

from decimal import Decimal
from datetime import datetime
from enum import Enum
from typing import List

class AccountType(Enum):
    ASSET = "asset"
    LIABILITY = "liability"
    EQUITY = "equity"
    REVENUE = "revenue"
    EXPENSE = "expense"

class Account:
    def __init__(self, code: str, name: str, account_type: AccountType):
        self.code = code
        self.name = name
        self.type = account_type
        self.balance = Decimal('0')
        self.debit_total = Decimal('0')
        self.credit_total = Decimal('0')

    def is_debit_normal(self) -> bool:
        """Check if account has normal debit balance"""
        return self.type in [AccountType.ASSET, AccountType.EXPENSE]

class JournalEntry:
    def __init__(self, date: datetime, description: str):
        self.id = self.generate_entry_id()
        self.date = date
        self.description = description
        self.lines = []
        self.posted = False

    def add_line(self, account: Account, debit: Decimal = None,
                 credit: Decimal = None):
        """Add line to journal entry"""
        if debit and credit:
            raise ValueError("Cannot have both debit and credit")

        self.lines.append({
            "account": account,
            "debit": debit or Decimal('0'),
            "credit": credit or Decimal('0')
        })

    def validate(self) -> bool:
        """Validate journal entry (debits must equal credits)"""
        total_debits = sum(line["debit"] for line in self.lines)
        total_credits = sum(line["credit"] for line in self.lines)

        return total_debits == total_credits

    def post(self) -> bool:
        """Post journal entry to ledger"""
        if not self.validate():
            raise ValueError("Entry does not balance")

        for line in self.lines:
            account = line["account"]
            if line["debit"]:
                account.debit_total += line["debit"]
            if line["credit"]:
                account.credit_total += line["credit"]

            # Update balance based on account type
            if account.is_debit_normal():
                account.balance = account.debit_total - account.credit_total
            else:
                account.balance = account.credit_total - account.debit_total

        self.posted = True
        return True

Financial Statement Generation

class FinancialStatements:
    def __init__(self, company_name: str, period_end: datetime):
        self.company_name = company_name
        self.period_end = period_end
        self.accounts = []

    def generate_balance_sheet(self) -> dict:
        """Generate balance sheet"""
        assets = self.sum_accounts_by_type(AccountType.ASSET)
        liabilities = self.sum_accounts_by_type(AccountType.LIABILITY)
        equity = self.sum_accounts_by_type(AccountType.EQUITY)

        # Calculate retained earnings
        revenue = self.sum_accounts_by_type(AccountType.REVENUE)
        expenses = self.sum_accounts_by_type(AccountType.EXPENSE)
        net_income = revenue - expenses

        total_equity = equity + net_income

        return {
            "company": self.company_name,
            "period_end": self.period_end,
            "assets": {
                "current_assets": self.get_current_assets(),
                "non_current_assets": self.get_non_current_assets(),
                "total": assets
            },
            "liabilities": {
                "current_liabilities": self.get_current_liabilities(),
                "non_current_liabilities": self.get_non_current_liabilities(),
                "total": liabilities
            },
            "equity": {
                "share_capital": equity,
                "retained_earnings": net_income,
                "total": total_equity
            },
            "balanced": assets == (liabilities + total_equity)
        }

    def generate_income_statement(self, period_start: datetime,
                                   period_end: datetime) -> dict:
        """Generate income statement (P&L)"""
        revenue = self.sum_accounts_by_type(AccountType.REVENUE)
        expenses = self.sum_accounts_by_type(AccountType.EXPENSE)

        gross_profit = revenue - self.get_cogs()
        operating_expenses = self.get_operating_expenses()
        operating_income = gross_profit - operating_expenses

        interest_expense = self.get_interest_expense()
        tax_expense = self.calculate_tax(operating_income - interest_expense)

        net_income = operating_income - interest_expense - tax_expense

        return {
            "company": self.company_name,
            "period": f"{period_start.date()} to {period_end.date()}",
            "revenue": revenue,
            "cogs": self.get_cogs(),
            "gross_profit": gross_profit,
            "operating_expenses": operating_expenses,
            "operating_income": operating_income,
            "interest_expense": interest_expense,
            "tax_expense": tax_expense,
            "net_income": net_income,
            "eps": self.calculate_eps(net_income)
        }

    def generate_cash_flow_statement(self) -> dict:
        """Generate cash flow statement"""
        return {
            "operating_activities": self.calculate_operating_cash_flow(),
            "investing_activities": self.calculate_investing_cash_flow(),
            "financing_activities": self.calculate_financing_cash_flow(),
            "net_change_in_cash": self.calculate_net_cash_change(),
            "beginning_cash": self.get_beginning_cash(),
            "ending_cash": self.get_ending_cash()
        }

Tax Calculations

class TaxCalculator:
    def calculate_corporate_tax(self, taxable_income: Decimal,
                                jurisdiction: str = "US") -> dict:
        """Calculate corporate income tax"""
        if jurisdiction == "US":
            tax_rate = Decimal('0.21')  # Federal rate
        elif jurisdiction == "UK":
            tax_rate = Decimal('0.19')
        else:
            tax_rate = Decimal('0.25')  # Default rate

        tax_amount = taxable_income * tax_rate

        return {
            "taxable_income": taxable_income,
            "tax_rate": tax_rate,
            "tax_amount": tax_amount.quantize(Decimal('0.01')),
            "effective_rate": tax_rate,
            "jurisdiction": jurisdiction
        }

    def calculate_vat(self, net_amount: Decimal, vat_rate: Decimal) -> dict:
        """Calculate VAT/Sales tax"""
        vat_amount = net_amount * vat_rate
        gross_amount = net_amount + vat_amount

        return {
            "net_amount": net_amount,
            "vat_rate": vat_rate,
            "vat_amount": vat_amount.quantize(Decimal('0.01')),
            "gross_amount": gross_amount.quantize(Decimal('0.01'))
        }

    def calculate_depreciation(self, cost: Decimal, salvage_value: Decimal,
                              useful_life_years: int,
                              method: str = "straight_line") -> List[dict]:
        """Calculate depreciation schedule"""
        if method == "straight_line":
            annual_depreciation = (cost - salvage_value) / useful_life_years

            schedule = []
            book_value = cost

            for year in range(1, useful_life_years + 1):
                depreciation = annual_depreciation
                book_value -= depreciation

                schedule.append({
                    "year": year,
                    "depreciation": depreciation.quantize(Decimal('0.01')),
                    "accumulated_depreciation": (annual_depreciation * year).quantize(Decimal('0.01')),
                    "book_value": book_value.quantize(Decimal('0.01'))
                })

            return schedule

Financial Ratios

class FinancialRatios:
    @staticmethod
    def current_ratio(current_assets: Decimal, current_liabilities: Decimal) -> Decimal:
        """Liquidity ratio: Current Assets / Current Liabilities"""
        return (current_assets / current_liabilities).quantize(Decimal('0.01'))

    @staticmethod
    def quick_ratio(current_assets: Decimal, inventory: Decimal,
                    current_liabilities: Decimal) -> Decimal:
        """Acid test: (Current Assets - Inventory) / Current Liabilities"""
        return ((current_assets - inventory) / current_liabilities).quantize(Decimal('0.01'))

    @staticmethod
    def debt_to_equity(total_debt: Decimal, total_equity: Decimal) -> Decimal:
        """Leverage ratio: Total Debt / Total Equity"""
        return (total_debt / total_equity).quantize(Decimal('0.01'))

    @staticmethod
    def return_on_equity(net_income: Decimal, shareholders_equity: Decimal) -> Decimal:
        """ROE: Net Income / Shareholders' Equity"""
        return (net_income / shareholders_equity * 100).quantize(Decimal('0.01'))

    @staticmethod
    def return_on_assets(net_income: Decimal, total_assets: Decimal) -> Decimal:
        """ROA: Net Income / Total Assets"""
        return (net_income / total_assets * 100).quantize(Decimal('0.01'))

    @staticmethod
    def profit_margin(net_income: Decimal, revenue: Decimal) -> Decimal:
        """Net Profit Margin: Net Income / Revenue"""
        return (net_income / revenue * 100).quantize(Decimal('0.01'))

Best Practices

Accounting Systems

Implement proper internal controls

Segregation of duties

Regular account reconciliations

Maintain supporting documentation

Use accounting software with audit trails

Regular backups of financial data

Year-end closing procedures

Financial Reporting

Follow GAAP/IFRS standards

Consistent accounting policies

Clear disclosure of estimates

Timely financial statement preparation

Independent audit for larger entities

Management discussion and analysis (MD&A)

Tax Compliance

Maintain organized tax records

Track deductible expenses properly

Timely tax filing and payments

Quarterly estimated tax payments

Transfer pricing documentation

Tax planning throughout the year

Anti-Patterns

❌ Using cash accounting for large businesses
❌ No account reconciliations
❌ Missing audit trails
❌ Inconsistent revenue recognition
❌ Inadequate internal controls
❌ Poor documentation of transactions
❌ Late tax filing and penalties

Resources

FASB (Financial Accounting Standards Board): https://www.fasb.org/

IFRS Foundation: https://www.ifrs.org/

IRS Tax Information: https://www.irs.gov/

AICPA (American Institute of CPAs): https://www.aicpa.org/