Changes to AST?

[Propertygoesup]

My virgin buy to let is the same it's a fixed percentage of the balance for five years.
so I am keeping hold of the property and probably will rent myself to avoid the fees if I sold within the five years.
Once the five year fix is up I will probably sell and buy somewhere for myself and...

[Propertygoesup]

Excellent thanks is there an official rent increase form or template?...

[Propertygoesup]

I have an AST for my tenant signed in July 2015 so this was before several changes were introduced.
however I verbally agreed to increase the rent slightly and defer payment by 10 days to fit with tenants new job. (15th to 25th).
Is this ok if both parties agree?
Or should any forms...