Tax and VAT · 8 min read · Updated: 2026-10-14

How the tax calendar works: your own deadlines and estimated amounts

The tax calendar brings together, on one screen, only the filing and payment dates that apply to you. It works out weekend and holiday shifts itself, estimates your VAT from your invoices and alerts your phone before the deadline.

In short

• The calendar is filtered by the sole proprietor/company, VAT, employee, e-Fatura and e-Defter details in your company profile; items that don't apply to you aren't shown.
• If a deadline falls on a weekend or public holiday, the date moves to the next business day automatically; a holiday eve (half day) doesn't shift it, and deadlines extended by circular are handled separately.
• Estimated VAT is calculated by subtracting the VAT on your expenses and incoming invoices from the VAT on your sales invoices; cancelled invoices are excluded, and your accountant calculates the final amount.
• By default, reminders arrive 5 days and 1 day before the deadline, as a single combined notification per day; amounts aren't shown on the lock screen.
• The account reconciliation list shows purchases and sales with the same company totalling 5.000 TL or more excluding VAT for the period; Ba/Bs forms haven't been filed since September 2024.

Deniz, the founder of Atlas Kahve, knew VAT was due on the 28th. But she only ever remembered the withholding tax return on the 26th, the SGK premium at the end of the month and the provisional tax in November when her accountant (mali müşavir) messaged her.

The tax calendar comes to you without waiting for that message. In this guide we cover the screen, how the calendar is filtered for your business, where the estimated amounts come from and how to set up reminders.

Part 1 · Tour What's on this screen?

Open the tax calendar with the Tax calendar link under Insights in the side menu. There are four indicators at the top and four tabs below them.

The two nearest obligations also appear in a small card on the home page; for example, "VAT return: 4 days left · estimated 18.400 TL".

Part 2 · Personalization Why does the calendar look different for everyone?

A sole proprietorship files annual income tax, while a limited company files corporate tax. A business with no employees doesn't deal with the muhtasar (withholding tax) return or the premium service return. The calendar reads these differences from your company profile.

• Business type: The sole proprietor/company choice you made at sign-up is used; companies see corporate tax, sole proprietors see annual income tax.
• Insured employees: If there's an active record on the Employees screen, this is automatically counted as Yes; it determines the withholding tax return and SGK (social security) premium.
• e-Fatura / e-Arşiv: If you've issued e-documents from Heyşirket, this is ticked automatically; if not, a warning about the e-Fatura (Turkish e-invoice) transition threshold is shown.
• e-Defter: The e-Defter (e-ledger) certificate upload and the year-end opening certification for paper ledgers appear based on this answer.

If a question hasn't been answered, the related item appears with a "Possible" badge and no reminder is sent for it. You can answer with a single tap from the Let's fine-tune your calendar box at the top of the Calendar tab.

Part 3 · Dates How are deadlines calculated?

The calendar starts from the legal deadline. Under the Tax Procedure Law (VUK), if the deadline falls on a public holiday, Saturday or Sunday, it extends to the next business day. The calendar makes this shift itself, including religious holidays, and notes the reason under the item.

Part 4 · Estimates Where do the estimated amounts come from?

Estimated KDV (VAT) is found by subtracting the VAT on expenses and incoming invoices for the same month from the VAT on your sales invoices for the selected month. Return invoices are deducted from the sales side, and cancelled invoices aren't counted at all.

VAT carried forward from the previous period, exemptions and documents not entered in the portal change the result. If deductible VAT is higher, the calendar shows "No payment expected · carried forward".

For the provisional tax item, the difference between sales excluding VAT and expenses from the start of the year to the end of the quarter appears as "period profit". Salaries, depreciation and changes in stock aren't reflected in this summary; discuss the amount with your accountant.

Part 5 · Notifications How do reminders work?

Setting up reminders

1. Open the company profile

   On the Tax calendar screen, switch to the Company profile tab.

2. Choose the days

   In the Reminders box, tick up to four of the 7 days before, 5 days before, 3 days before, 1 day before or On the deadline options. The default is 5 days and 1 day.

3. Decide on the email copy

   The notification and portal message always arrive; the email copy also includes the estimated amounts and can be turned off if you like.

4. Save

   Press the Save profile button. If more than one deadline is approaching on the same day, they're all combined into a single notification.

Your phone's lock screen shows only a short line such as "3 days left for the VAT return"; amounts and personal details aren't shown. No reminder is sent for an item you've marked Done.

Part 6 · Sharing Account reconciliation and a summary for your accountant

The Account reconciliation tab lists, with document counts, your sales and purchases with the same counterparty in the selected month that total 5.000 TL or more excluding VAT. This is the threshold of the Ba/Bs forms abolished in September 2024; today the list is used to compare records with the other party.

1. Check the email address on the row; if it isn't saved on your cari (customer/supplier account), you can type it in.
2. Send to a single company with Send reconciliation, or select rows and send to several with Send to selected. For bulk sending, you see the recipient list and tick a confirmation box.
3. The other party answers I confirm or Our records differ from the link in the email without signing in; when the reply arrives you get a notification and the row's status updates.

The Send to my accountant button at the top right sends the selected month's estimated VAT, the account totals above the threshold and document counts to the accountant email saved in Company profile. Add to calendar downloads an .ics file that adds upcoming deadlines to the calendar on your phone or computer.

Open your tax calendar Complete your company profile once, and your deadlines and estimated amounts will come to you automatically. Open calendar

Author: Heyşirket Editorial Team