Welcome to this week’s edition of The Bootstrap Insider (Thoughts of the Week).

While we send you curated pitch competitions and funding opportunities during the week, Sundays are reserved for something different. Every Sunday, I share my raw bootstrapping experiences and the internal systems I use to build my business. My goal is simple: to act as your guide, help you avoid the costly traps I fell into, and help you grow much faster ❤

Hi,

Before we dive deep into the numbers today, here is a very important disclaimer:

I am not a tax expert, accountant, or financial advisor. The world of taxes is highly individual and complex. When I started out three years ago, I found it incredibly difficult to find clear, understandable information on this topic. That’s why I am sharing my personal perspective today as a self-employed founder running a sole proprietorship (Einzelunternehmen) in Germany, without a corporate structure like a GmbH or UG. Choosing whether to set up a corporation or a partnership depends on strategic, operational, and liability reasons—they all have pros and cons, which we won't dive into today.

Now, let’s focus on the true hero of this story: You and your business.

You hustle day in and day out, you send out invoices, you celebrate your first revenues, and the money on your business account keeps growing. You feel successful. But in the background, a massive problem is quietly brewing—one that ruins countless bootstrappers every single year.

The government demands its very own personal "subscription"—and this is not an app provider you want to mess with. The tax office is ruthless. Many founders have absolutely no idea how much tax debt they are accumulating throughout the year. When the official tax assessment finally hits their mailbox months later, the shock follows: a massive minus, sleepless nights, and the raw fear of bankruptcy.

As an entrepreneur, it is your fundamental duty to know your numbers. Taxes should never catch you off guard. That is exactly why we have the third bucket in our system: The Tax Account. I use a strict rule for this: 25% of all incoming revenue goes straight into this account. How did I come up with that number? Let me guide you through the logic.

The simplified baseline formula for your sole proprietorship is:

Revenue minus Operating Expenses (OPEX) = Net Business Profit. If your profit exceeds the legal tax-free allowance (which is currently €24,500 in Germany), trade tax (Gewerbesteuer) applies first. The remaining profit then goes into your personal income tax return. This is where private expenses, like your health insurance or child allowances, are factored in to determine your actual taxable income.

In Germany (and many other countries), taxes operate on a progressive rate system. Simply put: The more you earn, the higher your percentage tax rate becomes.

To give you a feeling for this curve, here is a look at the typical tax burden (estimated values for the basic tariff):

To estimate your exact tax burden, I regularly use the official calculator provided by the German Federal Ministry of Finance: BMF Tax Calculator.

Let’s look at a concrete example (see above): Let’s assume you are married, filed jointly, and you have a combined taxable income of €80,000 in year 2025. According to the BMF calculator, this results in an average tax burden of roughly 18.30%.

This means you would owe a total of €14,640.00 in income tax for that year. Part of this might have already been paid through your spouse’s employment, but you need to have your share as a self-employed founder ready.

And this is exactly where our system kicks in: Because we consistently route 25% of our total revenue into the Tax Account, we easily cover that 18.30% tax on our profit while simultaneously building a comfortable safety buffer.

If you’ve made it this far: Congratulations! But here comes the part that most founders completely underestimate, and it represents the true danger to your liquidity.

The moment the tax office realizes you owe a retroactive tax payment, they don't just want that money for the past year—they want to secure their taxes for the future in advance.

The magic word here is prepayment (Vorauszahlung). Your retroactive payment amount is divided by four, and you are required to pay this amount every single quarter moving forward. That money isn't gone, but it is completely missing from your active cash flow. And in bootstrapping, Cash is King.

Let’s play out this emotional horror story using a real-world timeline:

Now, this is what happens: The tax office doesn't just demand the €12,000 retroactive payment within a few weeks. They simultaneously set a quarterly prepayment of €3,000 for the current year, due in the very next quarter (Q4).

This means: In Year 1, you suddenly have to put €15,000 in cash on the table! If you spent that money on business investments throughout the year because you thought it belonged to you, you are officially broke at this point.

The good news: This brutal double-hit is usually a one-time shock for new founders. Moving forward, these prepayments are recalculated and adjusted with every annual tax return you file. Eventually, you get into a steady rhythm where the prepayments perfectly match your actual tax burden, and it balances out at the end of the year. But you must have the cash reserves to survive that initial hit.

To avoid this fate, we use the following plan:

When you bring this level of discipline to your business, your anxiety transforms into absolute peace of mind. You won't face any nasty surprises, you secure your liquidity, and you will sleep like a baby while other founders tremble at the sight of a letter from the tax office.

We have officially survived the hardest, driest financial topics! You now know how to secure your personal survival (Payroll) and how to keep your expenses (OPEX) and taxes (TAX) locked down.

Next Sunday is going to be a lot more rewarding. We will finally talk about the accounts that are actually fun to manage: The Profit Account (your ultimate reward) and the Buffer Account for maximum entrepreneurial freedom.

Go check your bank accounts, adjust your percentages, and enjoy your Sunday!

Keep building,

Bartosz

In the upcoming editions, we’ll close out the system:

👉 25% Tax Reserve (Covered today!)

👉 3% Profit Account

👉 2% Buffer Account