Do you often work from home or use your private smartphone for business calls? Then you can deduct part of your internet and telephone costs from your taxes. Here you can find out how.


When are telephone and internet costs deductible?

This is how you use the lump sum for telephone and internet

Alternative: Record internet and telephone use individually

How to enter telephone and internet costs in the Taxfix app

When are telephone and internet costs deductible?

If your employer does not reimburse you for the business portion of your internet and telephone bills, you can deduct them from your taxes as income-related expenses.

There are two ways to claim telecommunication costs in your tax return:

As a lump sum

This means that you can deduct a flat rate of 20% of your total costs, up to a maximum of 20 euros per month or 240 euros per year.

With itemised receipts

This means that you document the professional portion of your costs with itemised receipts and can deduct this portion without limit.

With our app, you can either choose the lump sum or claim higher costs. We explain exactly how to do this at the end of this article.

The advantages and disadvantages of the two options are explained below:

This is how you use the lump sum for telephone and internet

Advantage of the flat rate: You have less effort - because you don't have to prove the extent to which you used your private connections for business purposes.

Disadvantage: Only up to 20% of your monthly telephone and internet expenses are recognised by the tax office as income-related expenses. The upper limit is 20 euros per month or 240 euros per year. Your telephone or internet bill would therefore have to be 100 euros per month to reach the maximum amount.

Prerequisite: You actually worked from home or made professional phone calls with your private smartphone.

This is how you calculate your lump sum:

Take the costs for three consecutive months and extrapolate them for the whole year. It is most worthwhile to select the months in which your telephone or internet costs were the highest. Alternatively, you can also take the annual average.


Steffi's private internet bill was most expensive in March, April and May.

Sum of the 3 bill amounts: 50 € + 43 € + 56 € = 149 €

149 € / 3 months * 20% = 9,93 €

9,93 € * 12 months = 119,16 €

Steffi can claim 119.16 euros in her tax return because the amount is below the limit of 240 euros.

Note that you can only claim the costs for the period of the year in which you actually used your internet and telephone for work. For example, if you were only in your home office for a few months, you can only deduct the costs for those months.

Alternative: Record internet and telephone use individually

Advantage of itemised deductions: You can deduct your expenses for professional use of your internet or telephone for an unlimited period of time - there is no maximum amount. This is particularly worthwhile if you suspect that the professional share is over 20%.

Disadvantage: You have more effort - because you have to document and calculate the professional share exactly.

Prerequisite: You must be able to present the individual record to the tax office upon request.

This is how itemised accounting works for telephone costs:

For three months in the year of assessment, you document all business and private telephone calls with date, time, duration and participants. Determine the share of business use with the help of your itemised bill or the recorded call duration.

For example, if you made 40% of your calls for business purposes, you can deduct 40% of the total invoice amount in the assessment period.

Good to know: With mobile phone contracts, you do not have to separate the costs for telephoning, surfing or texting, even if you have only made business calls, for example. You can use the entire invoice amount as a basis, including basic charges or provision costs.

This is how itemised billing works for internet costs:

You can claim internet costs in the same way if you work from your home office. To do this, you estimate how much you used your internet for business and private purposes. You enter the professional share of your internet costs in your tax return. According to a decision of the Lower Saxony Tax Court, an estimated professional use of up to 50% is accepted.

Once the tax office has accepted the individual record, the percentage determined is usually also valid for the tax returns of the following years.

How to enter telephone and internet costs in the Taxfix app

You can enter work-related internet and telephone costs in our app in the “Work” category.

Our app automatically calculates the costs to be applied in the tax year based on your details on the use of the connections and the monthly costs. If you have a combined internet and telephone connection, you only enter the monthly costs once.

The app takes the costs into account as follows:

  • If you did not use your phone/internet daily for work purposes, the app takes into account the flat rate, i.e. 20% of the costs

  • If you used your phone/internet daily, 50% of the recorded costs are taken into account in the app. Please note that if you use your phone/internet daily, the tax office will usually ask for receipts

  • Then enter the average monthly costs for your telephone/internet connection. The monthly costs cannot exceed 100 euros in the app

  • Finally, enter the number of months you used your phone/internet for work in the corresponding tax year

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