Local Housing Allowance and rent increase?

Is there anything that prevents a landlord from charging the full Local Housing Allowance (LHA) to DSS claimants?

The LHA is the amount that the DSS will pay in rent for a benefit claimant in a particular area, dependant on the number of rooms that they are entitled to. This LHA used to be capped to the bottom third or so of average rents in that area. This cap has recently risen quite substantially.

For example, in my area a person on benefits who qualifies for a two bed property can claim up to £550. This has risen from £470 at the start of the year.

I have a tenant who currently pays £450 for such a property, funded entirely by the DSS. It has occurred to me that I am being foolish by not seeking the maximum LHA rent from her, since it is the DSS that will pay.

So can I simply serve her with a Form 4 (Section 13(2)) proposed new rent and expect the DSS to fund her to the tune of £550 in full, or will there be some resistance from the DSS? (Standard AST, long term tenant, rent not increased for the last 2 years)

In case anyone thinks I am being selfish, I am simply looking at ways to afford the increase in tax we have to pay following the Section 24 rules.

Jessie