The turn of the year is the busiest stretch in a sole trader's calendar. What you do in December and January is what decides whether March is calm or frantic. Here is the whole sequence — step by step, with the dates and the decisions that belong to each month.
December: closing the year
December is when the preparation starts. Do not wait for January: some things are far easier to sort out while the year is still running.
1. Review the invoices you issued
Go through every invoice for the year and check:
- Completeness — is all the work invoiced? Any project you never billed?
- Payment status — which invoices are paid and which are not? Chase the unpaid ones now and ask for settlement before the year ends.
- Correctness — do the invoices carry everything they should: IČO (business ID), DIČ (tax ID), a description of the service, the amount?
- Numbering — is the series continuous, with no gaps?
In Taxorio this is a dashboard job: unpaid invoices and total income for the year are on the same screen, and you can filter invoices by status and period when you need a closer look.
2. Review received invoices and expenses
Expenses deserve the same attention as income. Check that:
- everything is recorded — go through the bank statements and compare them against the expenses in your records. Is any document missing?
- categories are right — software, hardware, services, travel, phone, office and the rest
- every expense has a document — invoice, receipt, or proof of payment. Track down what is missing while it can still be found.
AI document scanning is what makes a wallet full of receipts a manageable evening rather than a lost weekend: photograph them with your phone and the details are read for you to confirm.
3. Decide on large purchases
If a bigger purchase is coming — a new laptop, software, office equipment — consider making it in December. On actual expenses, a December purchase raises this year's expenses and lowers this year's tax base. On flat-rate expenses it makes no difference at all.
Watch the asset threshold: if the item costs more than 80 000 Kč, it cannot be claimed in one go. It has to be depreciated over several years under § 26–33 of the Income Tax Act.
4. Check your insurance advances
Make sure every monthly advance for social insurance (ČSSZ) and health insurance (VZP or whichever insurer you are with) has actually been paid. Social insurance advances are due within the calendar month they relate to, so the December advance is payable by 31 December; health insurance advances are due by the 8th day of the following month, so December's is payable by 8 January. Arrears carry penalties.
January: adding up and deciding
By January you have the full year's data and can start evaluating it.
5. Total up income and expenses
Work out the totals for the year. In Taxorio the financial dashboard already has them. The numbers you need:
- Total income — the sum of invoices actually paid, not invoices issued
- Total actual expenses — every deductible expense that has a document behind it
- Flat-rate expenses — 60 % of income for an unqualified trade, capped at 1 200 000 Kč
6. Flat-rate or actual expenses
Compare the two and take the better one. Most sole traders with low real costs — IT freelancers, consultants, creatives — end up on flat-rate expenses.
A worked example for 2026:
- Income: 900 000 Kč
- Actual expenses: 180 000 Kč
- Flat-rate expenses at 60 %: 540 000 Kč
Tax base on actual expenses: 720 000 Kč. On flat-rate expenses: 360 000 Kč. The choice makes itself, and it moves both the tax and the insurance contributions.
The decision applies to the whole year, retrospectively, and the two methods cannot be mixed: either flat-rate expenses against all income, or actual expenses against all income. Since 2018, when § 35ca of the Income Tax Act was repealed, flat-rate expenses no longer block any tax relief — the child tax credit and spouse relief included.
7. VAT and the control statement, if you are registered
Registered for DPH (VAT)? The December return and the control statement (kontrolní hlášení) are due by 25 January — the quarterly return for Q4 on the same date, and the control statement within the same deadline.
Taxorio exports the XML for both the control statement (DPHKH1) and the VAT return (DPHDP3) on the PRO plan; you upload the files to the Financial Administration portal.
February: statements and new advances
8. New insurance advances
Last year's income changes the size of your social and health insurance advances. The new health insurance advance applies from the month in which you file the annual statement, the new social insurance advance from the following month (see step 11). Until then you keep paying the old ones.
9. Gather what the return needs
Collect the documents you will need to complete the tax return:
- the income and expense summary — from the Taxorio dashboard
- confirmation of the insurance advances you paid
- a mortgage interest statement, if you claim it
- confirmation of blood donation or other donations, if you claim them
- statements for pension savings or life insurance
March and April: filing
10. The income tax return
The deadline depends on how it is filed:
- By you, on paper: by 1 April, three months after the end of the tax period. If 1 April falls on a weekend or a public holiday, it moves to the next working day.
- Electronically, through the data box: by 4 May 2026. Electronic filing automatically gets a month more; 1 May is a public holiday, so the 2025 deadline moves across the weekend to 4 May.
- Through a tax adviser: by 1 July, six months after the end of the tax period. The power of attorney has to be lodged with the tax office.
Taxorio generates the XML export for the personal income tax return (DPFDP7) on the PRO plan, ready to upload to the Financial Administration portal, so the figures do not have to be retyped. The export carries the self-employment part of the return (§ 7) and the basic taxpayer relief — the child tax credit, spouse relief, § 15 deductions and any tax advances already paid are added in the portal before you submit. The tax deadline overview lists the dates for the whole year.
11. The přehled for ČSSZ and your health insurer
After the tax return comes the přehled — the annual statement of income and expenses for the insurance authorities:
- ČSSZ — within one month of the tax return deadline. For 2025: 4 May 2026 if you filed by 1 April, or 2 June 2026 if you filed electronically after 1 April (the health insurer then has 4 June).
- Health insurer — within 30 days of the tax return deadline, on the same principle.
The statement shows whether you have underpaid or overpaid. An underpayment has to be settled within 8 days of filing the statement. An overpayment can be refunded or offset against future advances.
The checklist, month by month
December
- Review every issued invoice and its payment
- Track down missing expense documents
- Categorise all expenses correctly
- Consider large purchases before the year ends
- Confirm all insurance advances are paid
- VAT-registered: prepare the December VAT return
January
- Total income and expenses for the year
- Decide between flat-rate and actual expenses
- File the VAT return for December or Q4 by 25 January — VAT-registered only
- Start gathering documents for the tax return
February and March
- Collect every certificate for reliefs and deductions
- Complete the tax return, or hand the documents to your adviser
- VAT-registered: file the January and February returns
April and May
- File the tax return — for 2025, by 1 April 2026 on paper or 4 May 2026 electronically
- Pay any balance of tax
- File the přehled for ČSSZ, within 30 days of the return deadline
- File the přehled for your health insurer, within 30 days of the return deadline
- Settle any insurance underpayment
- Start paying the new advances at the new amounts
July, if you file through an adviser
- File the tax return by 1 July
- File both přehled statements within 30 days of that deadline
What Taxorio takes off the list
- Dashboard — income, expenses, VAT and unpaid invoices for any period, immediately
- Categorised expenses — so you know exactly what went on software, hardware, travel or services
- XML exports — DPFDP7 for the income tax return, DPHKH1 for the control statement, DPHDP3 for the VAT return, on the PRO plan. Export and upload.
- AI document scanning — a December evening is enough to digitise a year's worth of accumulated receipts
- Client records — every client detail in one place, with their invoice history
One closing recommendation: do not leave the preparation to the last moment. Recording income and expenses throughout the year — which is what the app is built around — turns December into a review rather than a reconstruction. And if something in your situation is unclear, talk to a tax adviser in good time; late or incorrect filings carry sanctions that are entirely avoidable.
Taxorio scope: Taxorio provides invoicing and income/expense records for Czech sole traders. It is not full accounting or personalised tax advice. For an unsupported or unusual case, verify the treatment with a Czech accountant or tax adviser before filing.