Income tax and advance tax: what an SMB actually owes and when

Get a small-business owner talking about tax, and the conversation almost always drifts to VAT. Yet VAT is not really your tax at all: you collect it from the customer and pass it to the state. The tax that actually bites at year-end is the one on your own earnings, namely income tax, corporate tax, and advance tax. All year you feel like things are going well, and then the tax due looks nothing like the balance in your bank account.

This article explains, in plain language, what these taxes are based on, when you pay them, and, most importantly, how advance tax shapes your cash flow. The goal is not to turn you into an accountant. It is to make you an owner who understands the numbers and never gets ambushed at year-end.

Tax is charged on profit, not turnover

This is where the most common mistake starts: confusing turnover with profit. A shop with high monthly sales thinks, "I am making a lot." But tax is not charged on your total sales; it is charged on profit, on what is left after you subtract every cost.

A simple example. Picture a handmade-candle workshop. Over a month it sells 100 units and books a healthy amount of revenue. But wax, rent, shipping, packaging, and electricity eat up most of it. What gets taxed is not the revenue; it is the profit left after those costs. Your turnover can be large, yet if your profit is small, so is your tax. The reverse is true too.

1Revenue2Subtract costs3Profit4Tax base

So talking about tax without seeing your real profit is guesswork. Keeping a steady record of income and expenses lets you predict the year-end picture months in advance. See the profit, and you can foresee the tax.

Income tax or corporate tax? Your legal form decides

What your tax is called, and how you pay it, depends on your legal structure. The distinction looks small, but it changes your rate, your calculation, and your filing calendar entirely.

• Sole proprietors, individuals trading in their own name, pay income tax on their profit. Income tax is usually progressive: as profit rises, the rate applied climbs in steps.
• Companies, such as limited and joint-stock companies, pay corporate tax, generally a single flat rate on profit whatever the amount.

Which rate applies, and the bracket thresholds, are updated most years and differ by country. That is why we explain the logic instead of quoting numbers. Confirm the current rates and the right structure for you with a licensed accountant (in Turkey, a mali müşavir). For some businesses a sole proprietorship is cheaper; once profit passes a certain level, incorporating can make more sense.

Your structure also shapes how you keep the books. It helps to know what the balance sheet and income statement actually show, because it is the income statement that reveals the profit your tax is based on.

Advance tax: paying the annual bill in installments

Here is the line item that surprises owners most: advance tax (in Turkey, geçici vergi). The state does not wait a full year to collect your income or corporate tax. Instead it takes the tax up front, in installments, based on your profit for periods during the year. Those prepayments are advance tax.

The logic is simple. At the end of each period you work out that period's profit, declare advance tax on it, and pay. When the year ends you file your annual return, and the advance tax you paid during the year is deducted from the final bill. So advance tax is not an extra tax; it is the same tax, paid early in pieces.

The number of periods and the deadlines vary by country and change from time to time, so confirm the current calendar with your accountant. The one thing to hold onto: tax does not wait for December. Every profitable period returns as a payment soon after.

What lowers the tax, and what does not

Since tax is charged on profit, anything that legally lowers your profit lowers your tax too. But the key phrase is "legal and documented." Spending with no receipt, no invoice, or no connection to the business cannot be booked as a cost.

Lowers thebaseDocumented costsDepreciationPayroll costsPrior-year losses

• Documented business costs: rent, materials, shipping, software subscriptions, and marketing, all direct and documented spending, reduce the base.
• Depreciation: the cost of a machine, vehicle, or computer is written off over several years rather than all at once. Knowing how depreciation works helps you plan how big purchases hit your tax.
• Payroll costs: salaries and the employer's social-security contributions sit on the cost side too.
• Prior-year losses: under set rules, losses from earlier years can be offset against later years' profit.

What can and cannot be expensed often comes down to fine detail, and this is where an accountant genuinely earns the fee. The aim is not to dodge tax; it is to record every legitimate cost, in full and with documents. And that rests on orderly pre-accounting: if the document does not get lost, neither does the deduction.

The cash-flow trap: profitable but broke

Now the most important sentence in this article: profit is not the money in your bank account. Tax is charged on profit, but the cash behind that profit usually is not sitting in your till.

On paper you are profitable, but that profit may be locked in unpaid invoices, in stock on the shelf, or already spent.

An example: a two-person real-estate office earns good commissions across the year, and the books show a solid profit. But some of the money is waiting in deferred payments, and some went into a new office and advertising. The advance-tax due date arrives, the amount is clear, but there is no cash behind it. The business is profitable; at that moment, it is broke.

The way out of this trap is to see tax coming, as a future cost, from the start. Watching deferred payments closely, keeping steady track of cheques and promissory notes, helps ensure there is cash on hand when the bill lands.

Year-end: reconciliation and the final bill

When the year closes, the picture clears. Sole proprietors file an annual income-tax return; companies file a corporate-tax return. That return shows the whole year's profit and the tax that matches it.

The good news: the advance tax you paid through the year is deducted from this final bill. If you paid more advance tax than your real annual tax, the difference is either refunded or set against your other tax debts. If you paid less, you top up the remainder. The system balances itself at year-end, but meeting that balance prepared is on you.

A healthy filing depends on the accuracy of the records you kept all year. When every cash movement, invoice, and collection sits where it should, you do not spend the filing period wrestling with surprise corrections.

In practice: becoming a tax-ready business

Managing tax is not hard math; it is a habit. A few simple disciplines remove most of the "the tax is due and there is no money" panic.

• Set the tax aside early: at the end of each profitable period, put the estimated tax somewhere separate. That money is no longer yours to spend.
• Measure profit regularly: look at your real profit once a month. An early picture means early action.
• Do not lose the paperwork: every undocumented cost is extra tax paid. Document your spending so your base reflects reality.
• Talk to your accountant: rates, brackets, and calendars change. Set your annual plan against the current rules with a professional.

This article has deliberately quoted no rate, amount, or date; they change every year and depend on your situation. What matters more than any figure is knowing how the system works: tax is charged on profit, taken up front, and balanced at year-end.

Frequently asked questions

For a well-run business, tax is not a disaster; it is a predictable cost. The only thing that turns it into a surprise is losing sight of profit and cash. Bring your income, expenses, and collections into one place, Rocketly for instance, and watch them regularly, and you will see the coming tax load months ahead and meet the due date with the money ready. Leave the rest, the current rates, brackets, and filing calendar, to your accountant. Own the system, and it will not ambush you.