The only way to have a policy that is not date specific is to take an annual policy. Single trip policies require the dates to coincide with a rental agreement.
The price for an annual policy is only marginally more than a two week policy. In any case, if your trip is more than 17 days, you may find it more cost efficient to opt for an annual policy. The same goes if you are planning to hire a car on multiple trips within the year that your policy is valid. Regardless of what you choose, read the policy wording to check that your insurance covers you for your dates and for the country you are travelling in.
Should you have any further questions regarding purchasing your car hire excess insurance policy contact the MoneyMaxim team by either phone or live chat within our operating hours.