Invoicing and Debtor Policy

Which invoices can you expect from GTS?

GTS sends out invoices for services with regard to gas transport in the national grid.

The GTS invoices consist of a cover sheet (PDF file) and specification (XLS file). The PDF file is an overview giving the total amounts. The XLS file gives a detailed specification. The energy units used on our invoices is kWh by default, unless otherwise specified. The invoice specification always states the energy unit used.

We draw up these invoices at various times of the year. Most invoices, such as the contracted, balancing, peak supply, exceeding and settlement invoices, have a monthly pattern. There are also a number of invoices that are only sent once or twice per year, such as the gas heating and reconciliation invoices.

You can read more about when we send our invoices under ‘When can you expect which invoices?’

If you would like to know which services are invoiced on which invoice, you can also find this information under ‘What service is invoiced on which invoice?’

Where can you find your invoices?

GTS sends digital invoices. Invoices related to you with invoice date less than two years in the past are available in our customer portal Gasport. You can view your invoices after logging in on Gasport and then selection ‘Financial’ and ‘Invoices’. In the left menu, click on ‘Invoices’ (see the image below). In the bottom-left corner of your screen, you can select a time period for which you wish to view your invoices. You can also set up an e-mail reminder to notify you of new invoices in Gasport by sending an e-mail to

What service is invoiced on which invoice?

Contracted invoice
The contracted invoices contain all contracted services and administrative fees payable to GTS. The contracted services are specified per contract and per booking number. If you requested a transfer of capacity rights (TOC), transfer of usage right (TOU) or diversion (DIV), GTS will charge a fee per transfer/ diversion. You can find more information about the fees charged in Appendix 1c of the TSC. The contracted invoice also comprises a cover sheet and a specification. This specification is split up in a large number of tabs; below is an explanation of the various tabs.

The tab ‘CSV Total’ gives an overview of the total amounts per legal task.

The tab ‘TOC/TOU/DIVoverview shows the capacities traded with third parties. This tab is only shown if you actually traded capacities with third parties.

The tabs ‘Entry capacity’ and ‘Exit capacity’ are the contracted services per direction, entry and exit. The tabs entry and exit also give a specification of the monthly and daily bookings. In addition, the tab Exit specifies LDCs for parties active in the distribution network.

The tab ‘Trading fees’ shows the fees charged because one or more TOCs, TOUs or diversions were carried out in that month. This tab is only shown if you actually requested a TOC, TOU or diversion.

The tab ‘Surcharges’ is shown if you acquired capacity through an auction at border points and have entered an auction surcharge/auction premium, which was confirmed to you by the auction platform. Per booking, the capacity and premium per kWh is shown. Please note that the premium is given as €ct/kWh.

The tab ‘Wheeling’ is shown if you have contracted wheeling. You can read more about wheeling and the various options in our TSC.

Below is an example of a contracted invoice and invoice specification.

Balancing invoice

The balancing invoice is used to invoice the Within-Day Balancing Actions (WDBA) and Line Pack Flexibility Services (LFS). Balancing actions, required because the SBS prognosis is exceeding the green zone, are charged to the causing parties. You will only see these on your invoice if, at the time of the delivery, you caused a balancing action. The LFS is the portfolio imbalance settlement which is settled at the end of each gas day against an percentage and the applicable neutral gas price (NGP). Below is an example of this invoice.

Peak supply advance and final invoice

You will receive the peak supply invoice from GTS if you are a supplier in a distribution network in the G1A or G2A segment  (small scale users), or if you are a LB shipper and have signed the third-party agreement for a number of suppliers as their shipper. The form for this agreement can be found below. The peak supply invoice is used to charge the reservation that GTS has to effect for small-scale users for peak supply. The invoice is drawn up based on the connection registers “het centraal aansluitregister (C-AR)” of the distribution network operators. The reservation is calculated based on the first monthly communications (M1, advance invoice) and then four months later based on the final data from the C-AR (M+4,final invoice). Below is an example of these invoices.

You can read more about peak supply here.

Capacity exceeding invoice

The capacity exceeding invoice is drawn up if the contracted daily entry or exit capacity at a network point is exceeded by more than the operational 2% margin per hour. Only the highest capacity excess value is charged per gas day.

The excess value is based on the difference between the booked capacity and actual used capacity, multiplied by the applicable monthly factor and yearly rate for the network point (transport rate + balancing rate + quality conversion rate for the respective network point).

Settlement advance and final invoice

The settlement invoice is the invoice comparing the near-real time (NRT) portfolio imbalance with the offline portfolio imbalance. This gives a settlement quantity which is settled against the neutral gas price (NGP). This is done twice for each gas month. The first time based on the provisional allocation, which results in the settlement advance invoice. We then carry out this process again four months later (M+4) based on the final allocations. This gives the settlement final invoice. This settlement final invoice charges any differences compared to the provisional allocation. These invoices only contain entries for those days when there was a difference between the provisional and final allocation.

Below are examples of het settlement advance and final invoices.

How can you check your invoice?

Contracted invoice
For the contracted invoice, you can consult the function "Contract Position" in Gasport. This also contains the original CDS numbers shown under Deal ID. These can be downloaded. In Gasport you can find a complete summary (conversion) with the CDS numbers and the new Booking ID for your bookings.

Balancing invoice
For the balancing invoice, you can check the balancing actions in Gasport. Go to ‘Historical’ and then select the option ‘Balancing’ (see the image below). The same applies to the LFS, which can also be found here.

Peak supply advance and final invoice
Suppliers active in a distribution network in the G1A or G2A segment and shippers in a distribution network who have signed the third-party agreement for an number of suppliers as their shipper receive a peak invoice.

The contracted peak delivery capacity is invoiced through two different invoices:

  • Transport costs + production costs: This invoice covers both the costs to reserve peak facilities and the reserved transport capacity. This invoice is only sent in the winter months (Jan, Feb, Dec).
  • Production costs: This invoice only shows the costs to reserve the peak facilities. This invoice is sent in the other months.

The winter invoice comprises an appendix with 4 tabs: 1 for entry, 1 for exit, 1 for production and 1 with the calculation parameters.

The summer invoice comprises an appendix with 2 tabs: 1 for production and 1 for the calculation parameters.

The advance invoice for reserved peak delivery capacity is sent on the first work day after the month of supply (based on M1 data). Four months later, based on the M4 data, the final invoice is drawn up. The final invoice charges the difference between the M1 and M4 values.

Capacity exceeding invoice
For the capacity exceeding invoices, you have to compare two screens in Gasport. Firstly, you have to request the contract position in Gasport. You can compare this with the hourly offline allocation in Gasport at the relevant network point. This allocation can be requested via ‘Historical’ and ‘Offline allocations’ (see the image below). Select the relevant time period in the left menu and the relevant network point you want to check to the right.

Settlement advance and final invoice
The settlement advance and settlement final invoices can also be checked with the data in Gasport. Go to ‘Historical’ and click ‘Settlement’. In the left menu, select the time period you want to check the settlement data for. The overview shows you the Near Real Time, the Offline V3 Imbalance and the Offline V4 Imbalance, as well as the Settlement Quantities on your invoice specification of the settlement advance and final invoices. If you want to check a specific hourly imbalance, double-click a line to show all Near Real Time and Offline Allocations for that specific hour.

When can you expect which invoice?

Invoicing is carried out via the invoice calendar. This calendar is displayed here.

  Invoice type Invoiced on Dec 2019 Jan Feb Mrt Apr May Jun Jul Aug Sep Oct Nov Dec
1a Contracted 1st working day 2 2 3 2 1 1 2 1 3 1 1 2 1
1b Contracted for RNB only* 5th working day 6 8 7 6 7 7 8 7 7 7 7 6 7
2 Balancing 1st working day 2 2 3 2 1 1 2 1 3 1 1 2 1
6 Settlement advance** 25th working day 5 8 5 6 2 11 9 6 4 4 5 4 4
7 Settlement final* 19th working day 30 28 27 26 29 28 26 27 27 25 27 26 28
8 Peak supply advance 1 working day 2 2 3 2 1 1 2 1 3 1 1 2 1
9 Peak supply final* 19th working day 30 28 27 26 29 28 26 27 27 25 27 26 28
10 Capacity exceeding 20th working day 24 28 27 26 29 28 26 27 27 25 27 26 28

 * Invoices of month of delivery + 4. All other invoices are month of delivery + 1
** Because of the 25th working day this invoice will pass the regular scheduled month

More information
For any further queries and/or comments, you are also very welcome to contact the GTS Customer Desk via +31 (0)50 521 33 33 of

Debtor policy

Invoices in Gasport

All invoices created by Gasunie Transport Services, based on the contractual obligation between GTS and its customers, are made available in the Gasport online customer portal. You can view a summary of all outstanding debit invoices under ‘Financial’ - ‘Accounts payable’:

Under ‘Invoices’, you can view a summary of all invoices: credit and debit invoices, outstanding and paid invoices:


Treatment of outstanding items

The due date for every new invoice is 14 days after the invoice date. If an invoice (or part of an invoice) remains unpaid, GTS will begin a debt collection procedure. The costs of this procedure will be passed on to the customer.

Debit and credit amounts with the same due date are automatically set off against each other by GTS. Credit amounts will not be paid out when the outstanding debit amount is higher than the credit amount. If there are several outstanding items, it is possible to coordinate, in advance, how outstanding items should be settled. If you would like to make these type of payment arrangements, please contact our Customer Desk.


Bills for interest

At the beginning of each month, interest is calculated on all invoices paid late and this amount is passed on to the client in a separate invoice.

If you have any further questions about this process, please contact the Customer Desk during working hours.


View all frequently asked questions


  • All invoices made by GTS are based on the contractual obligation that customers enter into with GTS. The invoice are made available in the online customer portal Gasport. Under 'Financial'-'Accounts payable' is a list of all outstanding debit invoices.