Why Filing a Tax Return Is Worth It for Investors
The 25% withholding tax is automatically withheld by the bank. But in many cases, you’re paying too much: exemption orders that were forgotten or improperly allocated, losses at different banks that weren’t offset, or your personal tax rate is below 25%. With the KAP form, you can claim back the difference.
per person (2026)
+ solidarity surcharge + child tax credit (if applicable)
for joint filing
Here’s how to optimize your capital gains tax
taxtastic automatically checks whether you’ve overpaid withholding tax and recovers the money for you.
Enter your investment income
Enter your annual tax statements from your banks. taxtastic automatically identifies areas with potential for optimization.
Tax Efficiency Check & Loss Offset
Is your tax rate below 25%? Do you have losses at one bank and gains at another? taxtastic calculates the optimal solution.
Secure Your Refund via ELSTER
Automatic verification and secure transmission. You’ll get a refund from the tax office for any withholding tax you overpaid.
Your Benefits in Capital Gains Optimization
taxtastic knows all the tricks to minimize your tax burden on investment income.
Most Favorable Rate Test
Is your personal income tax rate below 25%? If so, taxtastic automatically applies for the more-favorable tax rate test—you’ll only pay your lower rate.
Cross-Bank Loss Offset
Offset losses at Bank A against gains at Bank B. To do this, you’ll need a loss certificate (apply by December 15!) and your tax return.
Optimize your tax exemption order
Forgot to file or did you distribute it poorly? Use your tax return to claim a refund for any excess tax paid on income below the saver’s allowance.
Offsetting Losses on ETFs & Stocks
Offset stock losses against stock gains. Other losses (ETFs, interest) can be offset against all investment income.
Here’s How to Claim a Refund for Overpaid Taxes
A realistic example for an investor with accounts at multiple banks.
,200 Losses (stock sales): -€1,800
- Savings allowance: €1,000 (not fully utilized)
- Cross-bank loss offset: €1,800
- More favorable tax treatment: not applicable
- Correct church tax refund: €85
Why investors use taxtastic
Automatic optimization
taxtastic automatically identifies which strategy is most advantageous for you.
Investment KAP filled in automatically
All relevant fields are filled in correctly in euros based on your bank statements.
Validation check
Check for errors and missing information before submission.
ELSTER submission
Secure, direct transmission to the tax office.
Data securely stored in Germany
GDPR-compliant, SSL-encrypted, hosted in Germany.
Register and try it for free
See in advance how much you’ll get back. Pay only when you turn it in.
Frequently Asked Questions
Not always. If your bank has correctly withheld the flat-rate withholding tax and you don’t need to offset losses across banks, filing is optional. However, it’s often worth it if you’re using the “günstigerprüfung” (most favorable tax treatment test) or if you’ve forgotten to submit exemption orders.
If your personal income tax rate is below 25%, you can apply to have capital gains taxed at the lower rate. The tax office checks which option is more favorable—taxtastic submits the application automatically.
You request a loss certificate from the bank where the losses occurred by December 15. Then you list all the certificates in your tax return—taxtastic automatically offsets the losses.
Stock losses can only be offset against stock gains (loss offset restriction). Unoffset losses are carried forward to the next year.
€1,000 per person, €2,000 for joint filing (as of 2026). Investment income up to this amount is tax-free if an exemption order is in place.
How much does taxtastic cost?
- Income Tax Return
- Validation check
- One price—even for married couples
- Previous years: 4 for voluntary returns, up to 7 for mandatory returns
- Valuable tax tips
- All features of the BASIS plan
- Trade tax return
- Value-Added Tax Return
- Advance sales tax return
- Automatic EÜR. Includes depreciation, IAB, and all reserves.
- Integrated accounting tools
*Average tax refund based on taxtastic user data