Nine years ago, a significant tax reform in Germany shifted the obligation from presenting tax documents to simply retaining them. This means that when filing your tax return, you are generally no longer required to submit receipts, tax certificates, cash register receipts, or proof of payment. However, tax authorities may request these documents in specific situations, and proactively submitting them can expedite the processing of your return and any potential tax refund. This article delves into the circumstances where providing supporting documentation is advisable, based on the evolving guidelines and practices of tax administrations.

The Evolution of Tax Documentation Requirements

Historically, taxpayers were obligated to physically submit all supporting documents with their tax declarations. This often led to voluminous submissions and increased administrative burden for both taxpayers and tax offices. The introduction of the "Belegvorhaltepflicht" (document retention obligation) aimed to streamline this process. The principle is that taxpayers must keep their documents readily available for a potential audit, but not necessarily submit them upfront.

However, tax authorities reserve the right to request further clarification, particularly when certain "significant factual circumstances" are identified. While the once-common practice of publishing "review fields" (Prüffelder) by tax authorities, such as in North Rhine-Westphalia, has largely been discontinued, the underlying principle of scrutinizing specific situations remains. These review fields were intended to guide tax advisors and taxpayers on areas likely to receive closer examination, facilitating the proactive submission of relevant documents to expedite the review process.

The German tax system, while aiming for simplification, still requires a degree of diligence from taxpayers. Understanding when to provide evidence, even when not explicitly mandated, can prevent delays and potential disputes with the tax office. The list of "significant factual circumstances" is not exhaustive but provides a strong indication of areas that warrant extra attention. These guidelines often align with those issued by other federal states, such as Bavaria, suggesting a general consensus among tax administrations on what constitutes a situation requiring more detailed scrutiny.

Key Scenarios Requiring Supporting Documentation

The following scenarios, derived from an overview of common practices and recommendations from tax authorities, highlight situations where submitting supporting documents with your tax declaration is advisable for individuals. This proactive approach can significantly speed up the assessment process and potentially lead to a quicker tax refund.

New Pension Contributions

For certain professional groups, alternative pension schemes exist outside the statutory pension insurance. These include pension plans for doctors, architects, lawyers, psychotherapists, and engineers, which serve as alternatives to the statutory pension system. For employees, employers typically handle contributions to these pension funds.

For individuals making their own contributions to these professional pension schemes for the first time, it is recommended to provide supporting documentation. This advice also extends to taxpayers making voluntary additional contributions to the statutory pension insurance. As Jana Bauer, managing director of the Federal Association of Income Tax Assistance Associations (BVL), explains, "Only regular pension contributions are electronically transmitted to the tax authorities. Voluntary payments require explicit documentation." This distinction is crucial, as voluntary contributions, often made to optimize tax liabilities, may not be automatically recognized by the tax system without explicit proof. The Inland Revenue Office (Finanzamt) will likely require evidence of these initial payments to verify the deduction.

Significant Donations

Donations to charitable organizations can be deducted as special expenses on tax returns. For donations up to 300 euros, a bank transaction confirmation, such as a bank statement or a cash deposit receipt, is generally sufficient. For larger amounts, a donation receipt from the charitable organization is necessary. However, for what the tax authorities deem "significant donations," the tax administration in North Rhine-Westphalia advises submitting supporting documentation directly with the tax return.

The tax authorities do not specify a precise monetary threshold for what constitutes a "significant donation." According to the Upper Finance Directorate of North Rhine-Westphalia, the assessment depends on the individual case, considering both the absolute amount of the donation and its proportion to the taxpayer’s taxable income. This case-by-case approach underscores the importance of providing clear evidence when a donation is substantial relative to one’s financial standing, as it might be flagged for closer examination to ensure compliance with charitable donation regulations.

Alimony Payments

Tax authorities often view alimony payments with a degree of scrutiny due to potential for abuse. Since the tax year 2025, such payments can only be deducted if they have been transferred to a bank account. Furthermore, the tax office consistently requires proof that the recipient of the support is indeed in need.

Typical alimony situations include parents providing financial support to their children during their studies, provided the parents no longer receive child benefits for them. The key condition is that the supported child must have minimal personal income and assets. If a child earns more than 624 euros per year, these earnings will be offset against the alimony payments claimed by the parent.

For individuals supporting recipients abroad, specific alimony declarations must be completed and verified by local authorities in the recipient’s country of residence. The German Federal Central Tax Office (Bundeszentralamt für Steuern) provides forms in various languages for this purpose, which should be attached to the tax declaration. The complexity and potential for misrepresentation in international alimony arrangements necessitate thorough documentation.

Application for Unlimited Tax Liability

Individuals without a residence in Germany are generally not subject to unlimited tax liability in the country. While this might seem advantageous initially, it can lead to significant disadvantages if the individual earns income in Germany. Without unlimited tax liability, they cannot benefit from tax allowances such as the basic personal allowance (Grundfreibetrag).

Those who apply for unlimited tax liability under Section 1, Paragraph 3 of the Income Tax Act (Einkommensteuergesetz) are advised by the tax authorities in NRW to submit supporting documents. Unlimited tax liability may be granted if an individual, despite not having a residence in Germany, earns at least 90 percent of their income within the country or if their foreign income does not exceed the basic personal allowance. The intention behind requiring documentation in this scenario is to verify the extent of economic ties to Germany and ensure fair taxation based on the individual’s overall financial situation.

Tax Relief for Severance Payments

Individuals who received a severance payment, compensation, or remuneration for long-term employment in the previous year may need to act swiftly with their tax declarations. Since 2025, the tax advantage for such payments is no longer considered by employers when calculating wage tax. Instead, affected individuals must now claim this more favorable tax treatment through their tax return.

The underlying principle is the "Fünftelregelung" (one-fifth rule), which treats a lump-sum payment as if it were spread over five years. This effectively reduces the overall tax burden. The NRW tax administration recommends submitting supporting documents for these situations. The rationale is to ensure that the one-fifth rule is applied correctly, as it is a specific tax relief provision that requires careful calculation and verification. Without proper documentation, the benefit might be overlooked or disputed.

Home Office Expenses

Taxpayers claiming expenses for a home office often face scrutiny from tax authorities. This is understandable, as the size of the dedicated space and the proportion of housing costs can lead to substantial tax savings. The ability to deduct these costs is strictly regulated.

Full deduction of home office expenses is permitted only if the room constitutes the focal point of the individual’s entire professional or business activity. Furthermore, the space must be used exclusively for work and contain no private items such as a bed, wardrobe, or hobby equipment. When these conditions are met, costs can be deducted as income-related expenses (Werbungskosten).

However, the tax authorities’ approach to verifying home office claims can vary. Daniela Karbe-Geißler from the Federation of German Taxpayers points out, "Many tax offices have their own forms for recording the home office, which taxpayers must fill out. Simply sending receipts may not suffice." This highlights the need to adhere to specific procedural requirements and provide comprehensive documentation that clearly delineates the work-related nature of the space.

An alternative for those who do not have a dedicated home office or whose space does not meet the strict criteria is the home office flat rate (Homeoffice-Pauschale). This allows employees to claim six euros per day worked from home, capped at 1,260 euros annually. This flat rate is accessible even to those working at their kitchen table or in a guest room, offering a simplified deduction.

First-Time Double Household Management

Tax authorities are particularly attentive when expenses appear for the first time in a tax return. This includes situations involving a double household maintained for professional reasons. To have a second residence recognized by the tax office, the commute to work from this secondary residence must be significantly shorter than from the primary residence. Monthly accommodation costs for this second household can be deducted up to 1,000 euros.

To substantiate these claims, it is advisable to submit supporting documents with the tax return, such as the rental agreement, proof of registration (Ummeldung), and potentially invoices for furnishing the apartment. "The plausibility is usually established by the new address of the employer and the second residence at the place of employment," explains Bauer. This requirement aims to prevent the misuse of deductions for multiple residences and ensure that the expenses are genuinely linked to professional necessity.

Travel Expenses

Individuals claiming business-related travel expenses in their tax return should also submit supporting documents, according to the NRW tax administration. In practice, employers’ confirmations of out-of-town work activities are often requested, as noted by Karbe-Geißler. Additionally, confirmation that the employer did not cover these costs may also be sought. This ensures that the claimed travel expenses are legitimate business expenditures and not personal costs being disguised as tax-deductible items.

First-Time Foreign Income

As soon as taxpayers earn income from abroad for the first time, they should submit documentation related to this income. The NRW tax administration specifies that this applies to taxpayers receiving income from non-self-employment or pensions abroad, or income that must be declared in the "Anlage AUS" (foreign income) form. This includes income from private asset disposals. Furthermore, documentation is also required for individuals moving out of Germany or returning to Germany, and these declarations should be supported by relevant documents in the "Anlage WA-Est" form.

Capital Investment Losses

Taxpayers experiencing losses from capital investments are also advised by the NRW tax administration to submit supporting documents. A bank’s tax certificate is suitable for this purpose. While financial institutions automatically remit capital gains tax (Abgeltungsteuer) to the treasury, the data from tax certificates is not directly transmitted to the tax authorities. Therefore, providing these certificates is crucial for claiming losses and ensuring they are correctly offset against other income.

Tax on Substitute Basis of Assessment

In some instances, the sale of securities may be subject to taxation based on a substitute basis of assessment. This can occur if the bank is unaware of the original acquisition costs of the securities, for example, if a securities account was transferred from abroad to a German bank. In such cases, 30 percent of the proceeds from the sale are considered profit. Lower profits must be documented. If the profit was higher and the investor does not report this, it could lead to accusations of tax evasion. The submission of relevant transaction documents and the bank’s confirmation of the original purchase price are therefore essential.

First-Time Rental and Lease Income

Similar to home office expenses, the specific documentation requirements for rental and lease income can vary among tax offices. "If someone is renting out a property and claiming a depreciation allowance for the first time in their tax return, it is best to submit the purchase price allocation directly," advises Karbe-Geißler. The tax office will inquire about this in every case. This is because only the costs related to the building itself are tax-deductible; the value of the land typically depreciates over time. Therefore, when purchasing a property that includes land, it is recommended to have a clear allocation of the purchase price documented by the notary.

Income from Cryptocurrencies

Investors in cryptocurrencies can also expect inquiries from tax authorities. The trading of Bitcoin, Ethereum, and other digital currencies is treated as a private disposal transaction for tax purposes. Profits remain tax-free if the total profits from private disposals in a calendar year are less than 1,000 euros. Furthermore, profits are tax-free if the coins are held for longer than one year. "If investors trade intensively with cryptocurrencies, they can quickly lose track of taxes, which is why tax offices pay close attention and request detailed statements as evidence," says Karbe-Geißler. This highlights the need for meticulous record-keeping of all crypto transactions.

Child-Related Costs

Expenses for childcare, such as for crèches, kindergartens, or after-school programs, are classified as special expenses. From 2025 onwards, parents can deduct 80 percent of up to 6,000 euros per child annually – amounting to 4,800 euros – as special expenses, an increase of 800 euros compared to previous years. For children of school age, fees for private schools are also deductible. These can be declared in the "Anlage Kind" (child-related expenses) form. Annually, up to 30 percent of school fees, capped at 5,000 euros, can be recognized as special expenses.

In both scenarios – childcare and private school fees – submitting supporting documents such as contracts, invoices, and proof of payment with the initial tax declaration is recommended. This initial documentation is crucial for establishing the legitimacy of these expenses with the tax authorities.

Energy Efficiency Measures

Property owners seeking to improve the energy efficiency of their owner-occupied home or apartment and claim tax deductions must provide documentation. The renovation must involve a certified professional company that issues a formal certificate detailing the measures undertaken. "Without this certificate, prepared according to official mẫu, the investment will not be tax-recognized, so it must be submitted with the tax return," states Bauer. This requirement ensures that only genuine energy-saving investments qualify for tax relief and that the work is carried out by qualified professionals.

Extraordinary Burdens

The list of recommended documentation also includes situations involving the first-time declaration of a disability or a change in the degree of disability (GdB). This will be the last time such documentation is required with the 2025 tax return. From January 1, 2026, the GdB will be automatically transmitted electronically from the relevant authorities to the tax office for new determinations or changes, streamlining the process.

Broader Implications and Official Stance

The shift towards a "Belegvorhaltepflicht" reflects a broader trend in tax administration aimed at digitalization and efficiency. However, it places a greater onus on taxpayers to maintain accurate and organized records. The scenarios outlined above are not exhaustive but represent areas where tax authorities are likely to request or scrutinize documentation.

The underlying principle is that taxpayers should be able to substantiate any claims made on their tax returns. Proactively submitting relevant documents in these "significant factual circumstances" can lead to a smoother and faster tax assessment process, potentially avoiding delays in receiving tax refunds or preventing unnecessary inquiries from the tax office. It is always advisable to consult with a tax advisor or refer to official guidance from the German tax authorities for specific situations.

This article was originally published in March 2025. It was reviewed and updated on July 9, 2026.