Figures released by the Scottish Govern-ment show that after three quarters of the financial year, less than half of the cash available was allocated.
Around half of those who applied for a discretionary housing payment were given cash, with an average payout being £303.
More than 16,000 applications were made to Glasgow City Council and 8819 awards given.
The city has £6.7m available from cash provided by the UK Government and the Scottish Government.
However the £3.5m allocated by the Scottish Government was announced only in October and the council expects that it will be spent by the end of the financial year.
A spokesman said another £1m has been spent since November.
Housing campaigners welcomed the cash but said tenants must be aware they can apply.
Shelter Scotland director Graeme Brown said: "For the full transformative effect of the Scottish Govern-ment's extra £20m it promised this year and next to be felt, Shelter Scotland urges local authorities to ensure those who need help know that it is available and help them apply for it."
The Scottish Govern-ment said it has provided the most cash it is allowed to under Westminster rules.
Deputy First Minis-ter Nicola Sturgeon said: "That money has enabled councils to top up their discretionary housing payments to the maximum amount Westminster legislation allows and help hard-pressed households."
Labour welfare spokeswoman Jackie Baillie said councils need £50m to mitigate the full extent of the bedroom tax and called for a no evictions policy.