The group, founded by private equity pioneer Edi Truell, beat rivals such as SAP to land the government as a client, adding to a blue chip list which includes firms like Aviva, Unilever and Glaxosmithkline.
Tungsten raised £160m from a listing on the Alternative Investment Market earlier this year and acquired a bank to help finance its network.
The group yesterday said it had processed $152bn (£91bn) of invoices last year versus $126bn in the prior year, but it fell to a full-year loss due to investment into the business.
Truell told City A.M. the group was mulling a secondary listing in New York at some point to help to build on Tungsten’s growth in the States, where a majority of its clients are based.
Tungsten, which was previously called OB10 until Truell bought the firm, offers suppliers early access to payments for invoices which have already been approved.
The group said it expected to double revenues every year thanks to the increase in e-invoicing.