Porsche SE is likely to hold back on a decision to merge with Volkswagen AG at its board meeting on Thursday as the holding company’s controlling families can’t agree on measures to reduce debt, according to people familiar with the situation.

The merger is due to be discussed by the boards of both companies at separate meetings on Thursday but Bloomberg News has been told that Porsche’s supervisory board may delay a decision until 29 July at the earliest.

VW’s supervisory board plans to discuss a proposal to take over Porsche’s operating unit in two steps valuing the company at EUR8bn (US$11.4bn) as part of a transaction that would involve an investment by the Gulf state of Qatar.

Sources said the negotiations were hindered by a possible tax charge if VW completely takes over Porsche AG. The Sueddeutsche Zeitung newspaper said the bill could be as much as EUR3bn (US$4bn).

Porsche SE accumulated an estimated EUR10bn (US$13.5) debt acquiring a 51% stake in VW and options for another 20% of the company. Reports last weekend said the Porsche and Piech families that control Porsche SE had agreed to sell the car making business to VW for about EUR8bn to lower the debt. The plan involves selling 49.9% of Porsche now and the remaining equity later.

Porsche CEO Wendelin Wiedeking favours a plan to cut Porsche’s debt by selling as much as 25% of the company to the Qatar Investment Authority for about EUR5bn (US$6.7bn).