FAQ
Short answers about the tool and about German tax with a US broker. The chapters under "Taxes" cover each topic in more depth.
The tool
Is this tax advice?
No. capi.tax prepares your data and does not constitute tax advice. It reads your broker export, converts the amounts to euro, applies the rules of German tax law and gives you a structured summary for your tax return. The figures are a starting point, not a final verdict. For your personal situation, please review the result and talk to a tax advisor (Steuerberater).
Is my data safe?
Yes. Your data never leaves your computer. Everything is calculated in your own browser, so there is no upload and no copy on a server. We have no technical way to see your transactions. Once you close the page, the data is gone.
Can I verify that?
Yes. Open your browser's developer tools, switch to the network tab and process a file: you will see the application load, but no upload of your data. The only other requests go to eu.i.posthog.com, our anonymous usage statistics without amounts or securities — see What we measure. Or load the page once, disconnect from the internet, and calculate anyway.
Do I need an account?
No. There is no sign-up, no login and no email prompt. You load your file and get your result.
What does it cost?
capi.tax is currently free. It is a private project — feedback is very welcome. There is no subscription, no payment details and no account.
Do I still need a tax advisor?
Not necessarily. Many people enter the figures themselves. For special cases — corporate actions, portfolio transfers, holdings bought before 2009 — a tax advisor is worth it. The PDF report is made for that. Shares bought before 2009 are tax-free on sale (§ 52 Abs. 28 S. 11 EStG); for fund units bought before 2009, only the gains since 1 January 2018 are taxable, with a €100,000 allowance (§ 56 Abs. 6 S. 1 Nr. 2 InvStG). capi.tax knows neither.
Brokers & files
Which brokers are supported?
Interactive Brokers and Tastytrade. Plus every introducing broker on the IBKR platform — LYNX and CapTrader among them: their Activity Statement comes out of the same IBKR system, so you simply pick Interactive Brokers.
Which file do I need?
From Interactive Brokers the Activity Statement as CSV (not Excel, not PDF); from Tastytrade the transaction export with All Transactions, as CSV. Interactive Brokers also accepts a Flex Query as XML; the Interactive Brokers guide explains which to pick. For Tastytrade, the guide is under Tastytrade.
Which tax years are supported?
Tax years from 2021 to the last completed year. For earlier years the Anlage KAP line numbers are not verified, so we do not offer them. For each year capi.tax uses that year's form lines and parameters (such as Teilfreistellung rates and the Basiszins), but the current law including retroactive changes: the €20,000 cap on forward-transaction losses is not applied for 2021 to 2024 either, because the 2024 Annual Tax Act removed it for all open cases (§ 52 Abs. 28 S. 25 f. EStG).
I have several accounts — what now?
Export one file per account and calculate each account on its own — several files in one run are meant only for the years of the same account. FIFO runs per custody account anyway: if you hold the same share in two accounts, the holdings are treated separately. For Anlage KAP you then add up the per-account figures line by line — lines 19, 20, 22, 23 and 41, and for 2021 to 2024 also lines 21 and 24. Don't add up net results or reference taxes.
My file is not recognised
Check three things: is it really CSV — or XML for Interactive Brokers — and not .xls or PDF? Is it from the broker you selected? And does the export contain all sections — for IBKR that means trades, dividends, interest and fees? An export trimmed to a few sections produces incomplete totals.
The file is very large
That is normal for a full year's export; up to 50 MB is accepted. Since everything runs locally, the time depends on your machine. If you split the export anyway (by quarter, say), upload all parts together and make sure their periods don't overlap.
Can I upload several files at once?
Yes, several files of the same broker – for example the files of earlier years, so capi.tax finds your purchases from those years (see Upload earlier years), or at Interactive Brokers a statement of the following year up to 10 January for December's interest (see Interest). Several accounts, though, you calculate one after another and add up the figures.
Results & problems
Why are some trades missing from my totals?
If a position was opened before the chosen tax year — options bought in 2024 that expire in 2025, say — the closing trade needs the purchase. capi.tax finds purchases from earlier years when you upload those years' files as well, or one file covering several years – see Upload earlier years. Otherwise you add them as an opening position. If it is missing, capi.tax lists the trade as unmatched in the audit-trail tab and leaves it out of the totals. Exception: written options from a previous year need no opening position – see Options & writing options.
What do the warnings after processing mean?
They show where capi.tax skipped rows or filed them under a fallback — an unknown row type, a fund without a fund kind. None of it is passed over silently: better a visible warning than a quiet assumption inside a tax figure. Each notice is explained in Processing notices.
Can I save the result?
Nothing is stored on purpose — close the tab and it is gone. So export your report before you leave the page — as PDF, Excel, CSV or JSON. capi.tax cannot read a report back in later.
Can I try it without using my own data?
Yes. Test Sample File on the home page shows you a complete result built from sample data, with nothing to upload.
I found a mistake
Get in touch through the contact form. A description of the trade that looks wrong helps — please without attaching your broker file or personal data.
Why does my gain differ from the broker report?
Typical reasons are a different lot method at the broker, the conversion of each trade to euros at its own day's rate, and missing purchases from earlier years. The audit trail in capi.tax shows, for every sale, which purchases it was matched against.
Why does the reference tax differ from my tax assessment?
Because the Finanzamt applies the Sparer-Pauschbetrag, church tax, the Günstigerprüfung and loss carryforwards. capi.tax provides the taxable base, not the assessment.
Which figure goes into my tax return?
The values from the KAP Form tab, line by line — not the Net Result from the header. What each line means is in Anlage KAP, KAP-INV & SO.
My net result is lower than expected. Why?
First check the audit trail for unmatched sales and the processing notices for skipped rows. Both are missing from the totals.
Basics
Do I even have to declare income from a foreign account?
Yes. A German bank withholds the tax directly, which settles it. Interactive Brokers and Tastytrade do not — and because no German tax was withheld, you are required to declare it (§ 32d Abs. 3 EStG). That is an obligation, not an option. Only dividends of German shares are usually already settled by German withholding – see Dividends of German shares.
Why is this so much more work with a US broker?
Because you have no German Steuerbescheinigung. A German broker runs FIFO, currency conversion, withholding tax and loss offsetting for you and reports finished figures. A US broker gives you raw data — the classification is up to you.
How much tax is due on capital income?
25 % flat tax (§ 32d Abs. 1 EStG), plus 5.5 % solidarity surcharge on the tax and church tax if applicable. Effectively about 26.4 % without church tax and about 27.8–28.0 % with it. The solidarity-surcharge threshold that applies to other income does not apply here.
What if my personal tax rate is lower?
Then apply for the Günstigerprüfung (§ 32d Abs. 6 EStG). The tax office automatically uses whichever rate is better for you; there is no downside to requesting it.
Do I still get the Sparer-Pauschbetrag with a US broker?
Yes, just not at source. From 2023 you are entitled to €1,000 (filing alone) or €2,000 (jointly assessed); for 2021 and 2022 it was €801 and €1,602 (§ 20 Abs. 9 EStG). A foreign broker cannot apply an exemption order, so you claim the allowance through your tax return. It applies once across all your accounts combined.
Can I deduct my custody fees?
No. Ongoing costs are covered by the Sparer-Pauschbetrag (§ 20 Abs. 9 EStG). Transaction costs that belong directly to a purchase or sale do reduce that trade's gain.
Does Interactive Brokers issue a German tax certificate?
No. IBKR is not a domestic paying agent and therefore issues no German-style annual tax certificate. Your Activity Statement and your own breakdown serve as evidence.
Do I have to report my Interactive Brokers account to the tax office?
For tax purposes you report the account's income, not the account: in Anlage KAP and KAP-INV of your income tax return. If you file a return, all untaxed capital income belongs in it. If it exceeds the saver's allowance, you are generally also required to file. Separately, transfers of more than €12,500 to or from abroad can be reportable to the Bundesbank under § 67 AWV.
Is capital gains tax deducted at Interactive Brokers?
No, nothing is withheld on capital gains, option premiums or interest. The only deduction is foreign withholding tax on dividends, taken by the source country. Exception: on dividends of German shares, German Kapitalertragsteuer is already withheld – see Dividends of German shares.
Do I have to declare years with a loss?
It usually pays off: unused losses are only recorded and carried forward if you declare them (§ 20 (6) sentences 3 and 7, § 10d (4) EStG). The tax office does not record losses on its own.
Do I need the Tastytrade 1099 for the tax office?
No. The tax office expects euro figures under German law. As evidence you keep your Tastytrade transaction history and a traceable breakdown, such as the PDF or Excel report capi.tax produces.
Do I still file Anlage KAP if I only hold ETFs?
As a rule, yes, although the fund income itself goes on KAP-INV. The Finanzamt grants the Sparer-Pauschbetrag automatically; you need Anlage KAP to apply for the Günstigerprüfung (line 4), for church tax, for the foreign-tax credit (line 41, fund distributions included) and to state allowance already used at German banks. Details in Anlage KAP, KAP-INV & SO.
Can I give a US broker an exemption order?
No. Exemption orders (Freistellungsaufträge) only exist with domestic banks and brokers. With a foreign account you get the saver's allowance through your tax return.
Are my commissions taken into account?
Yes. Fees on purchase increase the acquisition cost, fees on sale reduce the proceeds – both go into the gain per trade. Ongoing costs such as custody or data fees are covered by the allowance.
Is there a solidarity surcharge on capital income even if I pay none otherwise?
Yes. The surcharge exemption threshold does not apply to the Abgeltungsteuer. Only if your capital income is taxed under the normal scale through the Günstigerprüfung can the surcharge drop away.
Which rules apply to earlier tax years?
Those of the year in question. capi.tax picks the rules from the tax year you select and supports years from 2021.
Shares & securities
Can I choose between FIFO and another method?
No. For securities held in collective custody, FIFO is prescribed (§ 20 Abs. 4 S. 7 EStG): the shares bought first count as sold first. This applies per security and per custody account.
Does the US wash-sale rule apply to me?
No. Germany has no wash-sale rule. Adjustments from US tax paperwork (a 1099, for instance) must not be carried into the German figures — the calculation runs on the actual executions under FIFO.
What applies to a stock split?
A split is tax-neutral. The total cost basis stays the same, only the per-share price is rescaled — and the original acquisition date is retained. If a reverse split pays out a fraction in cash, that small part is a sale. capi.tax carries stock splits forward (Tastytrade: only forward splits with a whole-number ratio; IBKR Flex: when the ratio is readable, reverse splits too) — see Corporate actions.
Does FIFO apply across several accounts?
No, FIFO applies per account. If you hold the same share with two brokers, calculate each account separately.
Funds & ETFs
Is tax due on an accumulating ETF even though nothing is paid out?
Yes, through the Vorabpauschale (§ 18 InvStG). It is built from the redemption price at the start of the year, the base rate and 70 %, capped at the year's rise in value and reduced by any distributions. If the fund falls in value, it is 0.
Which year does the Vorabpauschale belong to?
The following year. It is only deemed to accrue on the first working day of the next year (§ 18 Abs. 3 InvStG) — so the 2024 Vorabpauschale belongs on your 2025 return. This is a common mix-up.
Do US ETFs have a Vorabpauschale too?
Usually yes. Many US-domiciled ETFs are still investment funds under the InvStG. "US ETF" does not automatically mean "no Vorabpauschale".
Why do I have to set the fund type myself?
Because the Teilfreistellung depends on it — 30 % for equity funds, 15 % for mixed funds, 60 % or 80 % for property funds — and broker data does not carry this German classification. What counts is the fund's prospectus (Anlagebedingungen).
Does the Teilfreistellung reduce losses as well?
Yes, and it is easy to miss. If you sell equity-fund units at a loss, only 70 % of that loss is deductible.
Do I have to deduct the partial exemption myself?
No. In the Anlage KAP-INV you enter the gross values, and the tax office applies the partial exemption based on the line. capi.tax shows you the taxable share as a guide but outputs the gross values for the forms.
Does the partial exemption apply to bond ETFs?
No, bond and money market funds have 0 % partial exemption. Their income still belongs in the Anlage KAP-INV, on the lines for other funds.
Does the partial exemption apply on top of the saver's allowance?
Yes. The partial exemption first reduces the taxable fund income. The tax office then applies the saver's allowance to your total capital income, see Flat tax & allowance.
Is a REIT a real estate fund?
A single REIT is a company and is taxed like a share, without partial exemption. An ETF that invests in many REITs is an investment fund; whether it counts as a real estate fund depends on its fund terms.
Options & derivatives
When is a writer's premium taxed?
When it reaches you (§ 20 Abs. 1 Nr. 11 EStG), regardless of what happens to the option later. If you buy the option back afterwards, the premium you pay reduces your income — according to the prevailing view, from tax year 2024 in the year you pay it (§ 20 Abs. 1 Nr. 11 EStG as amended by the 2024 Annual Tax Act). For years up to 2023, the Federal Fiscal Court assigns it to the year in which you received the premium (BFH, judgment of 02.08.2022, VIII R 27/21). capi.tax follows the tax authority and books the buyback in the year of payment; for buybacks before 2024 it shows a notice about the ruling.
What happens when a purchased option expires worthless?
The premium you paid is a deductible loss. This was contested for a long time but has been settled by the Federal Fiscal Court and adopted by the tax authority.
Where do options belong on the tax return?
For private investors, on Anlage KAP — not Anlage SO. Up to and including 2024, writer premiums and forward transactions had their own lines there; since the 2025 form they are part of the total capital income, and losses also go on the line for losses other than share losses.
Is a loss on a written option I bought back deductible?
Yes. The buy-back premium reduces the premium received; if it is larger, a loss remains and falls into the general pot. On the 2021 to 2024 forms it goes in line 22, not line 24.
Losses
Which losses can I offset against what?
Losses from share sales only against gains from share sales (§ 20 Abs. 6 S. 4 EStG). Everything else — interest, dividends, funds, forward transactions — shares one common pool. Any loss left over is carried forward to the next year; there is no carryback.
Does the €20,000 cap on forward transactions still apply?
No. The separate loss bucket for forward transactions and its €20,000 cap were removed by the 2024 Annual Tax Act (JStG 2024), retroactively in all cases still open. Such losses can again be offset without limit against your other capital income.
Do I need a Verlustbescheinigung?
Not for the foreign broker. That certificate is an instrument of German banks, which run internal loss pools. A foreign broker runs none — you declare gains and losses directly and the tax office does the offsetting. It is different for losses in a German account: to offset them against your foreign income, you need a loss certificate from the German bank, which you request by 15 December of the year (§ 43a Abs. 3 S. 4 EStG).
Can I offset share losses against dividends?
No. Share losses only reduce gains from share sales, in the current year or in later years. Dividends belong to the general pot.
Are ETF losses share losses?
No. Fund units are not shares within the meaning of § 20 Abs. 6 S. 4 EStG. A loss on an equity ETF is first reduced by the partial exemption and then goes into the general pot, see Teilfreistellung.
How do loss offsetting and the saver's allowance interact?
Gains and losses are offset in the pots first; the tax office then deducts the saver's allowance from the remaining positive amount. The allowance does not increase a loss. More under Flat tax & allowance.
Withholding tax
How much US withholding tax can I credit?
At most the rate the US is allowed to keep under the double-taxation treaty: 15 % on dividends — and at most 25 % per item of income (§ 32d Abs. 5 EStG). With a valid W-8BEN the US withholds exactly those 15 %, and all of it is creditable.
And if 30 % was withheld?
Without a W-8BEN the US withholds 30 %. Only 15 % is creditable even so — you do not recover the other 15 % through the German return, only through a refund procedure with the US tax authority.
Is unused withholding tax refunded or carried forward?
Neither. The credit is applied per individual item of income and per country; any excess lapses.
Why is my creditable withholding tax lower on funds?
Because the tax base is already reduced by the Teilfreistellung. For an equity fund (30 %), only 70 % of €15 withheld — €10.50 — is creditable.
Where do I find the withholding tax at CapTrader?
In the annual statement, in the Withholding Tax section right next to the dividends, and in the dividend report under Tax Documents. capi.tax reads it from the statement and matches it to the respective dividend.
And German shares in a LYNX account?
According to LYNX, German capital gains tax of 26.375 % (including solidarity surcharge) is already withheld on dividends of German shares – via the central securities depository Clearstream (§ 44 Abs. 1 S. 4 Nr. 3 EStG). That settles the tax (§ 43 Abs. 5 S. 1 EStG): capi.tax leaves these dividends out of lines 18 and 19 and the tax out of line 41, and shows them separately on the Anlage KAP tab. You only declare them for the Günstigerprüfung or if you pay church tax – how, see Dividends of German shares.
What do I do with the 35 % Swiss withholding tax?
You credit 15 % in Germany and reclaim the other 20 % from the Swiss Federal Tax Administration. Only the creditable part goes in line 41.
Does this also apply to CapTrader or LYNX?
Both introduce accounts held at Interactive Brokers; withholding is deducted and reported the same way there. Whether capi.tax can read your export depends on the file format — see Interactive Brokers.
Do I have to enter withholding tax even if it is fully creditable?
Yes. The tax office only knows about the foreign tax from your return. Without an entry in line 41, you pay the full German tax on the dividend.
Interest & fees
Can I deduct margin interest from my option gains?
No. Debit interest is an expense, and beyond the saver's allowance expenses are not deductible from capital income (§ 20 Abs. 9 EStG). That applies even if you use the loan only for options trading.
Do I have to report interest below the saver's allowance?
Yes. Because your broker withholds no German tax, you report all capital income on Anlage KAP, small amounts included (§ 32d Abs. 3 EStG). The tax office then deducts the saver's allowance.
How is securities lending income (Stock Yield Enhancement) at IBKR treated?
That is not conclusively settled. Interactive Brokers books these payments in its interest section, so capi.tax treats them as interest in line 19. Some argue they are other income under § 22 Nr. 3 EStG (Anlage SO). For larger amounts, best clarify the classification with a tax advisor.
Does interest on a dollar balance also count as a currency gain?
The interest itself is capital income, converted at the rate on the day it is credited. Whether the interest-bearing dollar balance additionally triggers a currency gain when you exchange it later is a separate question — see Currency gains.
Currency
Which exchange rates apply?
Each transaction is converted at its own date (§ 20 Abs. 4 Satz 1 EStG): the cost at the purchase-day rate, the proceeds at the sale-day rate — not a yearly average and not the year-end rate. The law does not prescribe a particular rate source; capi.tax uses the Deutsche Bundesbank reference rates. That is why two trades of equal size in dollars can produce different euro results.
Are currency gains taxable?
It depends on whether the balance earns interest. A non-interest-bearing foreign-currency balance you convert back is a private disposal (§ 23 Abs. 1 S. 1 Nr. 2 EStG): taxable within one year, tax-free after more than a year; if your gains from such disposals stay below €1,000 in the year (up to 2023: €600), tax-free as well. For an interest-bearing balance, the tax authorities treat currency gains as capital income, with no holding period or threshold; that view is disputed. That is a different thing from your share's price gain, which is already inside the euro result. capi.tax calculates currency gains for Interactive Brokers (not for Tastytrade) and shows them on the KAP Form tab, but does not yet include them in the Anlage KAP lines, see currency gains.
Do I use the rate from the purchase date or the sale date?
Both: the acquisition cost is converted at the purchase date's rate, the proceeds at the sale date's rate. The gain in euros follows from that.
Why doesn't capi.tax use the exchange rate from Interactive Brokers?
capi.tax uses the published euro reference rate for every broker alike. Your broker's rate can differ slightly and is harder for third parties to check.
Is the currency gain in my share gain tax-free?
No. The exchange rate effect between buying and selling a share is part of the share result and is subject to the Abgeltungsteuer. The one-year rule applies only to gains on a non-interest-bearing foreign-currency balance itself (Anlage SO); for interest-bearing balances see Currency gains.
What happens with a trade on a weekend?
There is no reference rate for that day. capi.tax uses the last rate published before it, usually the preceding Friday's.
Are currency gains tax-free?
For a non-interest-bearing balance, yes, if more than a year passes between buying and converting back the foreign currency, or if your total gain from private disposals in the year stays below €1,000 (before 2024: €600). For an interest-bearing balance, the tax authorities apply neither a holding period nor a threshold.
Do I need to do anything if I only trade US shares?
Not for the exchange-rate effect in the share trades themselves: it is already inside the euro result. It only becomes relevant for dollars you hold as a balance and convert back.
Do currency gains go on Anlage KAP or Anlage SO?
It depends on the balance. Gains on a non-interest-bearing foreign-currency balance are private disposals for Anlage SO, taxed at your personal rate. Gains on an interest-bearing balance are treated by the tax authorities as capital income on Anlage KAP; that view is disputed.
Can I offset currency losses against share gains?
Not for a non-interest-bearing balance: losses under § 23 EStG can only be offset against gains from private disposals. If you follow the authorities' view for an interest-bearing balance, they are capital income subject to the rules there, see loss offsetting.
Forms
Where do my figures go on the forms?
Capital income on Anlage KAP, fund and ETF income on Anlage KAP-INV, private disposals such as gains on non-interest-bearing foreign-currency balances on Anlage SO (for interest-bearing balances see currency gains). With a foreign broker, Anlage KAP mainly uses line 19 (all foreign capital income), lines 20 and 23 (share gains and losses contained in it), line 22 (other losses) and line 41 (creditable withholding tax); for 2021 to 2024, lines 21 and 24 are added for options. The detailed mapping is under Anlage KAP, KAP-INV & SO.
Do I pay tax on line 20 on top of line 19?
No. Line 20 is an "of which" figure: the share gains are already inside line 19. The tax office uses line 20 only to apply the share-loss rule correctly.
Do I enter dividends gross or net?
Gross, before US withholding tax. The withholding tax goes separately into line 41 and is credited against your German tax.
Do these line numbers apply to later years too?
The line numbers here come from the 2021 to 2025 forms. If a future form changes, check the figures against the official instructions before copying them over.
capi.tax prepares your data and is not tax advice. Please review the figures and ask a tax advisor (Steuerberater) about your personal situation.